//package hliu.demo.collections;
//
///**
// * @author LiHaitao
// * @description ConcurrentHashMapDemo:
// * @date 2019/10/17 16:02
// **/
//public class ConcurrentHashMapDemo {
//
//package java.util.concurrent;
//
//import java.io.ObjectStreamField;
//import java.io.Serializable;
//import java.lang.reflect.ParameterizedType;
//import java.lang.reflect.Type;
//import java.util.*;
//import java.util.concurrent.atomic.AtomicReference;
//import java.util.concurrent.locks.LockSupport;
//import java.util.concurrent.locks.ReentrantLock;
//import java.util.function.*;
//import java.util.stream.Stream;
//
//
//    public class ConcurrentHashMap<K, V> extends AbstractMap<K, V> implements ConcurrentMap<K, V>, Serializable {
//        private static final long serialVersionUID = 7249069246763182397L;
//
//
//    /* ---------------- Constants -------------- */
//
//        /**
//         * node数组最大容量
//         */
//        private static final int MAXIMUM_CAPACITY = 1 << 30;
//
//
//        /**
//         * 默认初始值，必须是2的幂数
//         */
//        private static final int DEFAULT_CAPACITY = 16;
//
//        /**
//         * 数组可能最大值，需要与toArray（）相关方法关联
//         */
//        static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
//
//        /**
//         * 并发级别，遗留下来的，为兼容以前的版本
//         */
//        private static final int DEFAULT_CONCURRENCY_LEVEL = 16;
//
//        /**
//         * 负载因子
//         */
//        private static final float LOAD_FACTOR = 0.75f;
//
//        /**
//         * 链表转树的阀值，如果table[i]下面的链表长度大于8时就转化为树
//         */
//        static final int TREEIFY_THRESHOLD = 8;
//
//        /**
//         * 树转链表的阀值，小于等于6是转为链表，仅在扩容tranfer时才可能树转链表
//         */
//        static final int UNTREEIFY_THRESHOLD = 6;
//
//        /**
//         * 在转变成树之前，还会有一次判断，只有键值对数量大于 64 才会发生转换。
//         * 这是为了避免在哈希表建立初期，多个键值对恰好被放入了同一个链表中而导致不必要的转化。
//         */
//        static final int MIN_TREEIFY_CAPACITY = 64;
//
//        /**
//         * Minimum number of rebinnings per transfer step. Ranges are
//         * subdivided to allow multiple resizer threads.  This value
//         * serves as a lower bound to avoid resizers encountering
//         * excessive memory contention.  The value should be at least
//         * DEFAULT_CAPACITY.
//         */
//        private static final int MIN_TRANSFER_STRIDE = 16;
//
//        /**
//         * The number of bits used for generation stamp in sizeCtl.
//         * Must be at least 6 for 32bit arrays.
//         */
//        private static int RESIZE_STAMP_BITS = 16;
//
//        /**
//         * 2^15-1，help resize的最大线程数
//         */
//        private static final int MAX_RESIZERS = (1 << (32 - RESIZE_STAMP_BITS)) - 1;
//
//        /**
//         * 32-16=16，sizeCtl中记录size大小的偏移量
//         */
//        private static final int RESIZE_STAMP_SHIFT = 32 - RESIZE_STAMP_BITS;
//
//        /*
//     * Encodings for Node hash fields. See above for explanation.
//     */
//        static final int MOVED = -1; // hash for forwarding nodes （forwarding nodes的hash值）、标示位
//        static final int TREEBIN = -2; // hash值是-2  表示这是一个TreeBin节点
//        static final int RESERVED = -3; // hash for transient reservations
//        static final int HASH_BITS = 0x7fffffff; // usable bits of normal node hash （ReservationNode的hash值）
//
//        /**
//         * 可用处理器数量
//         */
//        static final int NCPU = Runtime.getRuntime().availableProcessors();
//
//        /**
//         * For serialization compatibility.
//         */
//        private static final ObjectStreamField[] serialPersistentFields = {new ObjectStreamField("segments", Segment[].class), new ObjectStreamField("segmentMask", Integer.TYPE), new ObjectStreamField("segmentShift", Integer.TYPE)};
//
//    /* ---------------- Nodes -------------- */
//
//        /**
//         * Node是最核心的内部类，它包装了key-value键值对，所有插入ConcurrentHashMap的数据都包装在这里面。
//         * 它与HashMap中的定义很相似，但是但是有一些差别，它对value和next属性设置了volatile同步锁，
//         * 它不允许调用setValue方法直接改变Node的value域，它增加了find方法辅助map.get()方法。
//         */
//        static class Node<K, V> implements Map.Entry<K, V> {
//            final int hash;
//            final K key;
//            //val和next都会在扩容时发生变化，所以加上volatile来保持可见性和禁止重排序
//            volatile V val;
//            volatile Node<K, V> next;
//
//            Node(int hash, K key, V val, Node<K, V> next) {
//                this.hash = hash;
//                this.key = key;
//                this.val = val;
//                this.next = next;
//            }
//
//            public final K getKey() {
//                return key;
//            }
//
//            public final V getValue() {
//                return val;
//            }
//
//            /**
//             * HashMap中Node类的hashCode()方法中的代码为：Objects.hashCode(key) ^ Objects.hashCode(value)
//             * 而Objects.hashCode(key)最终也是调用了 key.hashCode()，但是效果一样
//             */
//            public final int hashCode() {
//                return key.hashCode() ^ val.hashCode();
//            }
//
//            public final String toString() {
//                return key + "=" + val;
//            }
//
//            //不允许直接改变value的值
//            public final V setValue(V value) {
//                throw new UnsupportedOperationException();
//            }
//
//            /**
//             * HashMap使用if (o == this)，且嵌套if；ConcurrentHashMap使用&&
//             */
//            public final boolean equals(Object o) {
//                Object k, v, u;
//                Map.Entry<?, ?> e;
//                return ((o instanceof Map.Entry) && (k = (e = (Map.Entry<?, ?>) o).getKey()) != null && (v = e.getValue()) != null && (k == key || k.equals(key)) && (v == (u = val) || v.equals(u)));
//            }
//
//            /**
//             * 增加find方法辅助get方法 ，HashMap中的Node类中没有此方法
//             */
//            Node<K, V> find(int h, Object k) {
//                Node<K, V> e = this;
//                if (k != null) {
//                    do {
//                        K ek;
//                        if (e.hash == h && ((ek = e.key) == k || (ek != null && k.equals(ek))))
//                            return e;
//                    } while ((e = e.next) != null);
//                }
//                return null;
//            }
//        }
//
//    /* ---------------- Static utilities -------------- */
//
//        /**
//         * 对hashCode进行再散列，算法为(h ^ (h >>> 16)) & HASH_BITS
//         */
//        static final int spread(int h) {
//            return (h ^ (h >>> 16)) & HASH_BITS;
//        }
//
//        /**
//         * 返回大于等于count的最小的2的幂次方
//         */
//        private static final int tableSizeFor(int c) {
//            int n = c - 1;
//            n |= n >>> 1;
//            n |= n >>> 2;
//            n |= n >>> 4;
//            n |= n >>> 8;
//            n |= n >>> 16;
//            return (n < 0) ? 1 : (n >= MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : n + 1;
//        }
//
//        /**
//         * Returns x's Class if it is of the form "class C implements
//         * Comparable<C>", else null.
//         */
//        static Class<?> comparableClassFor(Object x) {
//            if (x instanceof Comparable) {
//                Class<?> c;
//                Type[] ts, as;
//                Type t;
//                ParameterizedType p;
//                if ((c = x.getClass()) == String.class) // bypass checks
//                    return c;
//                if ((ts = c.getGenericInterfaces()) != null) {
//                    for (int i = 0; i < ts.length; ++i) {
//                        if (((t = ts[i]) instanceof ParameterizedType) && ((p = (ParameterizedType) t).getRawType() == Comparable.class) && (as = p.getActualTypeArguments()) != null && as.length == 1 && as[0] == c) // type arg is c
//                            return c;
//                    }
//                }
//            }
//            return null;
//        }
//
//        /**
//         * Returns k.compareTo(x) if x matches kc (k's screened comparable
//         * class), else 0.
//         */
//        @SuppressWarnings({"rawtypes", "unchecked"}) // for cast to Comparable
//        static int compareComparables(Class<?> kc, Object k, Object x) {
//            return (x == null || x.getClass() != kc ? 0 : ((Comparable) k).compareTo(x));
//        }
//
//    /* ---------------- Table element access -------------- */
//
//    /*
//     * Volatile access methods are used for table elements as well as
//     * elements of in-progress next table while resizing.  All uses of
//     * the tab arguments must be null checked by callers.  All callers
//     * also paranoically precheck that tab's length is not zero (or an
//     * equivalent check), thus ensuring that any index argument taking
//     * the form of a hash value anded with (length - 1) is a valid
//     * index.  Note that, to be correct wrt arbitrary concurrency
//     * errors by users, these checks must operate on local variables,
//     * which accounts for some odd-looking inline assignments below.
//     * Note that calls to setTabAt always occur within locked regions,
//     * and so in principle require only release ordering, not
//     * full volatile semantics, but are currently coded as volatile
//     * writes to be conservative.
//     */
//
//        /**
//         * 获得在i位置上的Node节点
//         */
//        @SuppressWarnings("unchecked")
//        static final <K, V> Node<K, V> tabAt(Node<K, V>[] tab, int i) {
//            return (Node<K, V>) U.getObjectVolatile(tab, ((long) i << ASHIFT) + ABASE);
//        }
//
//        /**
//         * 利用CAS算法设置i位置上的Node节点（将c和table[i]比较，相同则插入v）。
//         */
//        static final <K, V> boolean casTabAt(Node<K, V>[] tab, int i, Node<K, V> c, Node<K, V> v) {
//            return U.compareAndSwapObject(tab, ((long) i << ASHIFT) + ABASE, c, v);
//        }
//
//        /**
//         * 利用volatile方法设置第i个节点的值，这个操作一定是成功的。
//         */
//        static final <K, V> void setTabAt(Node<K, V>[] tab, int i, Node<K, V> v) {
//            U.putObjectVolatile(tab, ((long) i << ASHIFT) + ABASE, v);
//        }
//
//    /* ---------------- Fields -------------- */
//
//        /**
//         * 存放node的数组,大小是2的幂次方
//         */
//        transient volatile Node<K, V>[] table;
//
//        /**
//         * 扩容时用于存放数据的变量，扩容完成后会置为null。
//         */
//        private transient volatile Node<K, V>[] nextTable;
//
//        /**
//         * 记录容器的容量大小，通过CAS更新
//         */
//        private transient volatile long baseCount;
//
//        /**
//         * 负数代表正在进行初始化或扩容操作 ,其中-1代表正在初始化 ,-N 表示有N-1个线程正在进行扩容操作
//         * 正数或0代表hash表还没有被初始化，这个数值表示初始化或下一次进行扩容的大小，类似于扩容阈值。
//         * 它的值始终是当前ConcurrentHashMap容量的0.75倍，这与loadfactor是对应的。实际容量>=sizeCtl，则扩容。
//         */
//        private transient volatile int sizeCtl;//控制标识符
//
//        /**
//         * The next table index (plus one) to split while resizing.
//         */
//        private transient volatile int transferIndex;
//
//        /**
//         * 自旋锁 （锁定通过 CAS） 在调整大小和/或创建 CounterCells 时使用。
//         * 在CounterCell类更新value中会使用，功能类似显示锁和内置锁，性能更好
//         */
//        private transient volatile int cellsBusy;
//
//        /**
//         * counter cell表，长度总为2的幂次
//         */
//        private transient volatile CounterCell[] counterCells;
//
//        // views
//        private transient KeySetView<K, V> keySet;
//        private transient ValuesView<K, V> values;
//        private transient EntrySetView<K, V> entrySet;
//
//
//    /* ---------------- Public operations -------------- */
//
//        /**
//         * 默认的构造函数
//         */
//        public ConcurrentHashMap() {
//        }
//
//        /**
//         * 指定容量的构造函数
//         *
//         * @param initialCapacity 初始化容量
//         * @throws IllegalArgumentException if the initial capacity of
//         *                                  elements is negative
//         */
//        public ConcurrentHashMap(int initialCapacity) {
//            if (initialCapacity < 0)
//                throw new IllegalArgumentException();
//            int cap = ((initialCapacity >= (MAXIMUM_CAPACITY >>> 1)) ? MAXIMUM_CAPACITY : tableSizeFor(initialCapacity + (initialCapacity >>> 1) + 1));
//            this.sizeCtl = cap;//初始化sizeCtl
//        }
//
//        /**
//         * 创建与给定map具有相同映射的新map
//         *
//         * @param m the map
//         */
//        public ConcurrentHashMap(Map<? extends K, ? extends V> m) {
//            this.sizeCtl = DEFAULT_CAPACITY;
//            putAll(m);
//        }
//
//        /**
//         * Creates a new, empty map with an initial table size based on
//         * the given number of elements ({@code initialCapacity}) and
//         * initial table density ({@code loadFactor}).
//         *
//         * @param initialCapacity 初始容量
//         * @param loadFactor      负载因子,当容量达到initialCapacity*loadFactor时，执行扩容
//         * @throws IllegalArgumentException if the initial capacity of
//         *                                  elements is negative or the load factor is nonpositive
//         * @since 1.6
//         */
//        public ConcurrentHashMap(int initialCapacity, float loadFactor) {
//            this(initialCapacity, loadFactor, 1);
//        }
//
//        /**
//         * Creates a new, empty map with an initial table size based on
//         * the given number of elements ({@code initialCapacity}), table
//         * density ({@code loadFactor}), and number of concurrently
//         * updating threads ({@code concurrencyLevel}).
//         *
//         * @param initialCapacity  初始容量
//         * @param loadFactor       负载因子,当容量达到initialCapacity*loadFactor时，执行扩容
//         * @param concurrencyLevel 预估的并发更新线程数
//         * @throws IllegalArgumentException if the initial capacity is
//         *                                  negative or the load factor or concurrencyLevel are
//         *                                  nonpositive
//         */
//        public ConcurrentHashMap(int initialCapacity, float loadFactor, int concurrencyLevel) {
//            if (!(loadFactor > 0.0f) || initialCapacity < 0 || concurrencyLevel <= 0)
//                throw new IllegalArgumentException();
//            if (initialCapacity < concurrencyLevel)   // Use at least as many bins
//                initialCapacity = concurrencyLevel;   // as estimated threads
//            long size = (long) (1.0 + (long) initialCapacity / loadFactor);
//            int cap = (size >= (long) MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : tableSizeFor((int) size);
//            this.sizeCtl = cap;
//        }
//
//        // Original (since JDK1.2) Map methods
//
//        /**
//         * {@inheritDoc}
//         */
//        public int size() {
//            long n = sumCount();
//            return ((n < 0L) ? 0 : (n > (long) Integer.MAX_VALUE) ? Integer.MAX_VALUE : (int) n);
//        }
//
//        /**
//         * {@inheritDoc}
//         */
//        public boolean isEmpty() {
//            return sumCount() <= 0L; // ignore transient negative values
//        }
//
//        /**
//         * 根据key在Map中找出其对应的value，如果不存在key，则返回null，
//         * 其中key不允许为null，否则抛异常
//         * 对于节点可能在链表或树上的情况，需要分别去查找
//         *
//         * @throws NullPointerException if the specified key is null
//         */
//        public V get(Object key) {
//            Node<K, V>[] tab;
//            Node<K, V> e, p;
//            int n, eh;
//            K ek;
//            int h = spread(key.hashCode());//两次hash计算出hash值
//            //根据hash值确定节点位置
//            if ((tab = table) != null && (n = tab.length) > 0 && (e = tabAt(tab, (n - 1) & h)) != null) {
//                // 搜索到的节点key与传入的key相同且不为null,直接返回这个节点
//                if ((eh = e.hash) == h) {
//                    if ((ek = e.key) == key || (ek != null && key.equals(ek)))
//                        return e.val;
//                } else if (eh < 0)//如果eh<0 说明这个节点在树上 直接寻找
//                    return (p = e.find(h, key)) != null ? p.val : null;
//                //否则遍历链表 找到对应的值并返回
//                while ((e = e.next) != null) {
//                    if (e.hash == h && ((ek = e.key) == key || (ek != null && key.equals(ek))))
//                        return e.val;
//                }
//            }
//            return null;
//        }
//
//        /**
//         * 检查table中是否含有key
//         *
//         * @param key possible key
//         * @return {@code true} if and only if the specified object
//         * is a key in this table, as determined by the
//         * {@code equals} method; {@code false} otherwise
//         * @throws NullPointerException if the specified key is null
//         */
//        public boolean containsKey(Object key) {
//            //直接调用get(int key)方法即可，如果有返回值，则说明是包含key的
//            return get(key) != null;
//        }
//
//        /**
//         * 检查在所有映射(k,v)中只要出现一次及以上的v==value，返回true
//         * 这个方法可能需要完全遍历Map，因此比containsKey要慢的多
//         *
//         * @param value value whose presence in this map is to be tested
//         * @return {@code true} if this map maps one or more keys to the
//         * specified value
//         * @throws NullPointerException if the specified value is null
//         */
//        public boolean containsValue(Object value) {
//            if (value == null)
//                throw new NullPointerException();
//            Node<K, V>[] t;
//            if ((t = table) != null) {
//                Traverser<K, V> it = new Traverser<K, V>(t, t.length, 0, t.length);
//                for (Node<K, V> p; (p = it.advance()) != null; ) {
//                    V v;
//                    if ((v = p.val) == value || (v != null && value.equals(v)))
//                        return true;
//                }
//            }
//            return false;
//        }
//
//        /**
//         * 直接调用putVal(key, value, false)方法
//         *
//         * @param key   key with which the specified value is to be associated
//         * @param value value to be associated with the specified key
//         * @return the previous value associated with {@code key}, or
//         * {@code null} if there was no mapping for {@code key}
//         * @throws NullPointerException if the specified key or value is null
//         */
//        public V put(K key, V value) {
//            return putVal(key, value, false);
//        }
//
//        /**
//         * putVal方法可以分为以下几步：
//         * 1、检查key/value是否为空，如果为空，则抛异常，否则进行2
//         * 2、进入for死循环，进行3
//         * 3、检查table是否初始化了，如果没有，则调用initTable()进行初始化然后进行 2，否则进行4
//         * 4、根据key的hash值计算出其应该在table中储存的位置i，取出table[i]的节点用f表示。
//         * 根据f的不同有如下三种情况：
//         * 1）如果table[i]==null(即该位置的节点为空，没有发生碰撞)，则利用CAS操作直接存储在该位置，如果CAS操作成功则退出死循环。
//         * 2）如果table[i]!=null(即该位置已经有其它节点，发生碰撞)，碰撞处理也有两种情况
//         * 2.1）检查table[i]的节点的hash是否等于MOVED，如果等于，则检测到正在扩容，则帮助其扩容
//         * 2.2）说明table[i]的节点的hash值不等于MOVED，如果table[i]为链表节点，则将此节点插入链表中即可
//         * 如果table[i]为树节点，则将此节点插入树中即可。插入成功后，进行 5
//         * 5、如果table[i]的节点是链表节点，则检查table的第i个位置的链表是否需要转化为树，如果需要则调用treeifyBin函数进行转化
//         */
//        final V putVal(K key, V value, boolean onlyIfAbsent) {
//            if (key == null || value == null)
//                throw new NullPointerException();// key和value不允许null
//            int hash = spread(key.hashCode());//两次hash，减少hash冲突，可以均匀分布
//            int binCount = 0;//i处结点标志，0: 未加入新结点, 2: TreeBin或链表结点数, 其它：链表结点数。主要用于每次加入结点后查看是否要由链表转为红黑树
//            for (Node<K, V>[] tab = table; ; ) {//CAS经典写法，不成功无限重试
//                Node<K, V> f;
//                int n, i, fh;
//                //检查是否初始化了，如果没有，则初始化
//                if (tab == null || (n = tab.length) == 0)
//                    tab = initTable();
//                /**
//                 * i=(n-1)&hash 等价于i=hash%n(前提是n为2的幂次方).即取出table中位置的节点用f表示。 有如下两种情况：
//                 * 1、如果table[i]==null(即该位置的节点为空，没有发生碰撞)，则利用CAS操作直接存储在该位置， 如果CAS操作成功则退出死循环。
//                 * 2、如果table[i]!=null(即该位置已经有其它节点，发生碰撞)
//                 */
//                else if ((f = tabAt(tab, i = (n - 1) & hash)) == null) {
//                    if (casTabAt(tab, i, null, new Node<K, V>(hash, key, value, null)))
//                        break;                   // no lock when adding to empty bin
//                } else if ((fh = f.hash) == MOVED)//检查table[i]的节点的hash是否等于MOVED，如果等于，则检测到正在扩容，则帮助其扩容
//                    tab = helpTransfer(tab, f);
//                else {//table[i]的节点的hash值不等于MOVED。
//                    V oldVal = null;
//                    // 针对首个节点进行加锁操作，而不是segment，进一步减少线程冲突
//                    synchronized (f) {
//                        if (tabAt(tab, i) == f) {
//                            if (fh >= 0) {
//                                binCount = 1;
//                                for (Node<K, V> e = f; ; ++binCount) {
//                                    K ek;
//                                    // 如果在链表中找到值为key的节点e，直接设置e.val = value即可
//                                    if (e.hash == hash && ((ek = e.key) == key || (ek != null && key.equals(ek)))) {
//                                        oldVal = e.val;
//                                        if (!onlyIfAbsent)
//                                            e.val = value;
//                                        break;
//                                    }
//                                    // 如果没有找到值为key的节点，直接新建Node并加入链表即可
//                                    Node<K, V> pred = e;
//                                    if ((e = e.next) == null) {//插入到链表末尾并跳出循环
//                                        pred.next = new Node<K, V>(hash, key, value, null);
//                                        break;
//                                    }
//                                }
//                            } else if (f instanceof TreeBin) {// 如果首节点为TreeBin类型，说明为红黑树结构，执行putTreeVal操作
//                                Node<K, V> p;
//                                binCount = 2;
//                                if ((p = ((TreeBin<K, V>) f).putTreeVal(hash, key, value)) != null) {
//                                    oldVal = p.val;
//                                    if (!onlyIfAbsent)
//                                        p.val = value;
//                                }
//                            }
//                        }
//                    }
//                    if (binCount != 0) {
//                        // 如果节点数>＝8，那么转换链表结构为红黑树结构
//                        if (binCount >= TREEIFY_THRESHOLD)
//                            treeifyBin(tab, i);//若length<64,直接tryPresize,两倍table.length;不转红黑树
//                        if (oldVal != null)
//                            return oldVal;
//                        break;
//                    }
//                }
//            }
//            // 计数增加1，有可能触发transfer操作(扩容)
//            addCount(1L, binCount);
//            return null;
//        }
//
//        /**
//         * Copies all of the mappings from the specified map to this one.
//         * These mappings replace any mappings that this map had for any of the
//         * keys currently in the specified map.
//         *
//         * @param m mappings to be stored in this map
//         */
//        public void putAll(Map<? extends K, ? extends V> m) {
//            tryPresize(m.size());
//            for (Map.Entry<? extends K, ? extends V> e : m.entrySet())
//                putVal(e.getKey(), e.getValue(), false);
//        }
//
//        /**
//         * Removes the key (and its corresponding value) from this map.
//         * This method does nothing if the key is not in the map.
//         *
//         * @param key the key that needs to be removed
//         * @return the previous value associated with {@code key}, or
//         * {@code null} if there was no mapping for {@code key}
//         * @throws NullPointerException if the specified key is null
//         */
//        public V remove(Object key) {
//            return replaceNode(key, null, null);
//        }
//
//        /**
//         * Implementation for the four public remove/replace methods:
//         * Replaces node value with v, conditional upon match of cv if
//         * non-null.  If resulting value is null, delete.
//         */
//        final V replaceNode(Object key, V value, Object cv) {
//            int hash = spread(key.hashCode());
//            for (Node<K, V>[] tab = table; ; ) {
//                Node<K, V> f;
//                int n, i, fh;
//                if (tab == null || (n = tab.length) == 0 || (f = tabAt(tab, i = (n - 1) & hash)) == null)
//                    break;
//                else if ((fh = f.hash) == MOVED)
//                    tab = helpTransfer(tab, f);
//                else {
//                    V oldVal = null;
//                    boolean validated = false;
//                    synchronized (f) {
//                        if (tabAt(tab, i) == f) {
//                            if (fh >= 0) {
//                                validated = true;
//                                for (Node<K, V> e = f, pred = null; ; ) {
//                                    K ek;
//                                    if (e.hash == hash && ((ek = e.key) == key || (ek != null && key.equals(ek)))) {
//                                        V ev = e.val;
//                                        if (cv == null || cv == ev || (ev != null && cv.equals(ev))) {
//                                            oldVal = ev;
//                                            if (value != null)
//                                                e.val = value;
//                                            else if (pred != null)
//                                                pred.next = e.next;
//                                            else
//                                                setTabAt(tab, i, e.next);
//                                        }
//                                        break;
//                                    }
//                                    pred = e;
//                                    if ((e = e.next) == null)
//                                        break;
//                                }
//                            } else if (f instanceof TreeBin) {
//                                validated = true;
//                                TreeBin<K, V> t = (TreeBin<K, V>) f;
//                                TreeNode<K, V> r, p;
//                                if ((r = t.root) != null && (p = r.findTreeNode(hash, key, null)) != null) {
//                                    V pv = p.val;
//                                    if (cv == null || cv == pv || (pv != null && cv.equals(pv))) {
//                                        oldVal = pv;
//                                        if (value != null)
//                                            p.val = value;
//                                        else if (t.removeTreeNode(p))
//                                            setTabAt(tab, i, untreeify(t.first));
//                                    }
//                                }
//                            }
//                        }
//                    }
//                    if (validated) {
//                        if (oldVal != null) {
//                            if (value == null)
//                                addCount(-1L, -1);
//                            return oldVal;
//                        }
//                        break;
//                    }
//                }
//            }
//            return null;
//        }
//
//        /**
//         * Removes all of the mappings from this map.
//         */
//        public void clear() {
//            long delta = 0L; // negative number of deletions
//            int i = 0;
//            Node<K, V>[] tab = table;
//            while (tab != null && i < tab.length) {
//                int fh;
//                Node<K, V> f = tabAt(tab, i);
//                if (f == null)
//                    ++i;
//                else if ((fh = f.hash) == MOVED) {
//                    tab = helpTransfer(tab, f);
//                    i = 0; // restart
//                } else {
//                    synchronized (f) {
//                        if (tabAt(tab, i) == f) {
//                            Node<K, V> p = (fh >= 0 ? f : (f instanceof TreeBin) ? ((TreeBin<K, V>) f).first : null);
//                            while (p != null) {
//                                --delta;
//                                p = p.next;
//                            }
//                            setTabAt(tab, i++, null);
//                        }
//                    }
//                }
//            }
//            if (delta != 0L)
//                addCount(delta, -1);
//        }
//
//        /**
//         * Returns a {@link Set} view of the keys contained in this map.
//         * The set is backed by the map, so changes to the map are
//         * reflected in the set, and vice-versa. The set supports element
//         * removal, which removes the corresponding mapping from this map,
//         * via the {@code Iterator.remove}, {@code Set.remove},
//         * {@code removeAll}, {@code retainAll}, and {@code clear}
//         * operations.  It does not support the {@code add} or
//         * {@code addAll} operations.
//         * <p>
//         * <p>The view's iterators and spliterators are
//         * <a href="package-summary.html#Weakly"><i>weakly consistent</i></a>.
//         * <p>
//         * <p>The view's {@code spliterator} reports {@link Spliterator#CONCURRENT},
//         * {@link Spliterator#DISTINCT}, and {@link Spliterator#NONNULL}.
//         *
//         * @return the set view
//         */
//        public KeySetView<K, V> keySet() {
//            KeySetView<K, V> ks;
//            return (ks = keySet) != null ? ks : (keySet = new KeySetView<K, V>(this, null));
//        }
//
//        /**
//         * Returns a {@link Collection} view of the values contained in this map.
//         * The collection is backed by the map, so changes to the map are
//         * reflected in the collection, and vice-versa.  The collection
//         * supports element removal, which removes the corresponding
//         * mapping from this map, via the {@code Iterator.remove},
//         * {@code Collection.remove}, {@code removeAll},
//         * {@code retainAll}, and {@code clear} operations.  It does not
//         * support the {@code add} or {@code addAll} operations.
//         * <p>
//         * <p>The view's iterators and spliterators are
//         * <a href="package-summary.html#Weakly"><i>weakly consistent</i></a>.
//         * <p>
//         * <p>The view's {@code spliterator} reports {@link Spliterator#CONCURRENT}
//         * and {@link Spliterator#NONNULL}.
//         *
//         * @return the collection view
//         */
//        public Collection<V> values() {
//            ValuesView<K, V> vs;
//            return (vs = values) != null ? vs : (values = new ValuesView<K, V>(this));
//        }
//
//        /**
//         * Returns a {@link Set} view of the mappings contained in this map.
//         * The set is backed by the map, so changes to the map are
//         * reflected in the set, and vice-versa.  The set supports element
//         * removal, which removes the corresponding mapping from the map,
//         * via the {@code Iterator.remove}, {@code Set.remove},
//         * {@code removeAll}, {@code retainAll}, and {@code clear}
//         * operations.
//         * <p>
//         * <p>The view's iterators and spliterators are
//         * <a href="package-summary.html#Weakly"><i>weakly consistent</i></a>.
//         * <p>
//         * <p>The view's {@code spliterator} reports {@link Spliterator#CONCURRENT},
//         * {@link Spliterator#DISTINCT}, and {@link Spliterator#NONNULL}.
//         *
//         * @return the set view
//         */
//        public Set<Map.Entry<K, V>> entrySet() {
//            EntrySetView<K, V> es;
//            return (es = entrySet) != null ? es : (entrySet = new EntrySetView<K, V>(this));
//        }
//
//        /**
//         * Returns the hash code value for this {@link Map}, i.e.,
//         * the sum of, for each key-value pair in the map,
//         * {@code key.hashCode() ^ value.hashCode()}.
//         *
//         * @return the hash code value for this map
//         */
//        public int hashCode() {
//            int h = 0;
//            Node<K, V>[] t;
//            if ((t = table) != null) {
//                Traverser<K, V> it = new Traverser<K, V>(t, t.length, 0, t.length);
//                for (Node<K, V> p; (p = it.advance()) != null; )
//                    h += p.key.hashCode() ^ p.val.hashCode();
//            }
//            return h;
//        }
//
//        /**
//         * Returns a string representation of this map.  The string
//         * representation consists of a list of key-value mappings (in no
//         * particular order) enclosed in braces ("{@code {}}").  Adjacent
//         * mappings are separated by the characters {@code ", "} (comma
//         * and space).  Each key-value mapping is rendered as the key
//         * followed by an equals sign ("{@code =}") followed by the
//         * associated value.
//         *
//         * @return a string representation of this map
//         */
//        public String toString() {
//            Node<K, V>[] t;
//            int f = (t = table) == null ? 0 : t.length;
//            Traverser<K, V> it = new Traverser<K, V>(t, f, 0, f);
//            StringBuilder sb = new StringBuilder();
//            sb.append('{');
//            Node<K, V> p;
//            if ((p = it.advance()) != null) {
//                for (; ; ) {
//                    K k = p.key;
//                    V v = p.val;
//                    sb.append(k == this ? "(this Map)" : k);
//                    sb.append('=');
//                    sb.append(v == this ? "(this Map)" : v);
//                    if ((p = it.advance()) == null)
//                        break;
//                    sb.append(',').append(' ');
//                }
//            }
//            return sb.append('}').toString();
//        }
//
//        /**
//         * Compares the specified object with this map for equality.
//         * Returns {@code true} if the given object is a map with the same
//         * mappings as this map.  This operation may return misleading
//         * results if either map is concurrently modified during execution
//         * of this method.
//         *
//         * @param o object to be compared for equality with this map
//         * @return {@code true} if the specified object is equal to this map
//         */
//        public boolean equals(Object o) {
//            if (o != this) {
//                if (!(o instanceof Map))
//                    return false;
//                Map<?, ?> m = (Map<?, ?>) o;
//                Node<K, V>[] t;
//                int f = (t = table) == null ? 0 : t.length;
//                Traverser<K, V> it = new Traverser<K, V>(t, f, 0, f);
//                for (Node<K, V> p; (p = it.advance()) != null; ) {
//                    V val = p.val;
//                    Object v = m.get(p.key);
//                    if (v == null || (v != val && !v.equals(val)))
//                        return false;
//                }
//                for (Map.Entry<?, ?> e : m.entrySet()) {
//                    Object mk, mv, v;
//                    if ((mk = e.getKey()) == null || (mv = e.getValue()) == null || (v = get(mk)) == null || (mv != v && !mv.equals(v)))
//                        return false;
//                }
//            }
//            return true;
//        }
//
//        /**
//         * Stripped-down version of helper class used in previous version,
//         * declared for the sake of serialization compatibility
//         */
//        static class Segment<K, V> extends ReentrantLock implements Serializable {
//            private static final long serialVersionUID = 2249069246763182397L;
//            final float loadFactor;
//
//            Segment(float lf) {
//                this.loadFactor = lf;
//            }
//        }
//
//        /**
//         * Saves the state of the {@code ConcurrentHashMap} instance to a
//         * stream (i.e., serializes it).
//         *
//         * @param s the stream
//         * @throws java.io.IOException if an I/O error occurs
//         * @serialData the key (Object) and value (Object)
//         * for each key-value mapping, followed by a null pair.
//         * The key-value mappings are emitted in no particular order.
//         */
//        private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException {
//            // For serialization compatibility
//            // Emulate segment calculation from previous version of this class
//            int sshift = 0;
//            int ssize = 1;
//            while (ssize < DEFAULT_CONCURRENCY_LEVEL) {
//                ++sshift;
//                ssize <<= 1;
//            }
//            int segmentShift = 32 - sshift;
//            int segmentMask = ssize - 1;
//            @SuppressWarnings("unchecked") Segment<K, V>[] segments = (Segment<K, V>[]) new Segment<?, ?>[DEFAULT_CONCURRENCY_LEVEL];
//            for (int i = 0; i < segments.length; ++i)
//                segments[i] = new Segment<K, V>(LOAD_FACTOR);
//            s.putFields().put("segments", segments);
//            s.putFields().put("segmentShift", segmentShift);
//            s.putFields().put("segmentMask", segmentMask);
//            s.writeFields();
//
//            Node<K, V>[] t;
//            if ((t = table) != null) {
//                Traverser<K, V> it = new Traverser<K, V>(t, t.length, 0, t.length);
//                for (Node<K, V> p; (p = it.advance()) != null; ) {
//                    s.writeObject(p.key);
//                    s.writeObject(p.val);
//                }
//            }
//            s.writeObject(null);
//            s.writeObject(null);
//            segments = null; // throw away
//        }
//
//        /**
//         * Reconstitutes the instance from a stream (that is, deserializes it).
//         *
//         * @param s the stream
//         * @throws ClassNotFoundException if the class of a serialized object
//         *                                could not be found
//         * @throws java.io.IOException    if an I/O error occurs
//         */
//        private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException {
//        /*
//         * To improve performance in typical cases, we create nodes
//         * while reading, then place in table once size is known.
//         * However, we must also validate uniqueness and deal with
//         * overpopulated bins while doing so, which requires
//         * specialized versions of putVal mechanics.
//         */
//            sizeCtl = -1; // force exclusion for table construction
//            s.defaultReadObject();
//            long size = 0L;
//            Node<K, V> p = null;
//            for (; ; ) {
//                @SuppressWarnings("unchecked") K k = (K) s.readObject();
//                @SuppressWarnings("unchecked") V v = (V) s.readObject();
//                if (k != null && v != null) {
//                    p = new Node<K, V>(spread(k.hashCode()), k, v, p);
//                    ++size;
//                } else
//                    break;
//            }
//            if (size == 0L)
//                sizeCtl = 0;
//            else {
//                int n;
//                if (size >= (long) (MAXIMUM_CAPACITY >>> 1))
//                    n = MAXIMUM_CAPACITY;
//                else {
//                    int sz = (int) size;
//                    n = tableSizeFor(sz + (sz >>> 1) + 1);
//                }
//                @SuppressWarnings("unchecked") Node<K, V>[] tab = (Node<K, V>[]) new Node<?, ?>[n];
//                int mask = n - 1;
//                long added = 0L;
//                while (p != null) {
//                    boolean insertAtFront;
//                    Node<K, V> next = p.next, first;
//                    int h = p.hash, j = h & mask;
//                    if ((first = tabAt(tab, j)) == null)
//                        insertAtFront = true;
//                    else {
//                        K k = p.key;
//                        if (first.hash < 0) {
//                            TreeBin<K, V> t = (TreeBin<K, V>) first;
//                            if (t.putTreeVal(h, k, p.val) == null)
//                                ++added;
//                            insertAtFront = false;
//                        } else {
//                            int binCount = 0;
//                            insertAtFront = true;
//                            Node<K, V> q;
//                            K qk;
//                            for (q = first; q != null; q = q.next) {
//                                if (q.hash == h && ((qk = q.key) == k || (qk != null && k.equals(qk)))) {
//                                    insertAtFront = false;
//                                    break;
//                                }
//                                ++binCount;
//                            }
//                            if (insertAtFront && binCount >= TREEIFY_THRESHOLD) {
//                                insertAtFront = false;
//                                ++added;
//                                p.next = first;
//                                TreeNode<K, V> hd = null, tl = null;
//                                for (q = p; q != null; q = q.next) {
//                                    TreeNode<K, V> t = new TreeNode<K, V>(q.hash, q.key, q.val, null, null);
//                                    if ((t.prev = tl) == null)
//                                        hd = t;
//                                    else
//                                        tl.next = t;
//                                    tl = t;
//                                }
//                                setTabAt(tab, j, new TreeBin<K, V>(hd));
//                            }
//                        }
//                    }
//                    if (insertAtFront) {
//                        ++added;
//                        p.next = first;
//                        setTabAt(tab, j, p);
//                    }
//                    p = next;
//                }
//                table = tab;
//                sizeCtl = n - (n >>> 2);
//                baseCount = added;
//            }
//        }
//
//        // ConcurrentMap methods
//
//        /**
//         * {@inheritDoc}
//         *
//         * @return the previous value associated with the specified key,
//         * or {@code null} if there was no mapping for the key
//         * @throws NullPointerException if the specified key or value is null
//         */
//        public V putIfAbsent(K key, V value) {
//            return putVal(key, value, true);
//        }
//
//        /**
//         * {@inheritDoc}
//         *
//         * @throws NullPointerException if the specified key is null
//         */
//        public boolean remove(Object key, Object value) {
//            if (key == null)
//                throw new NullPointerException();
//            return value != null && replaceNode(key, null, value) != null;
//        }
//
//        /**
//         * {@inheritDoc}
//         *
//         * @throws NullPointerException if any of the arguments are null
//         */
//        public boolean replace(K key, V oldValue, V newValue) {
//            if (key == null || oldValue == null || newValue == null)
//                throw new NullPointerException();
//            return replaceNode(key, newValue, oldValue) != null;
//        }
//
//        /**
//         * {@inheritDoc}
//         *
//         * @return the previous value associated with the specified key,
//         * or {@code null} if there was no mapping for the key
//         * @throws NullPointerException if the specified key or value is null
//         */
//        public V replace(K key, V value) {
//            if (key == null || value == null)
//                throw new NullPointerException();
//            return replaceNode(key, value, null);
//        }
//
//        // Overrides of JDK8+ Map extension method defaults
//
//        /**
//         * Returns the value to which the specified key is mapped, or the
//         * given default value if this map contains no mapping for the
//         * key.
//         *
//         * @param key          the key whose associated value is to be returned
//         * @param defaultValue the value to return if this map contains
//         *                     no mapping for the given key
//         * @return the mapping for the key, if present; else the default value
//         * @throws NullPointerException if the specified key is null
//         */
//        public V getOrDefault(Object key, V defaultValue) {
//            V v;
//            return (v = get(key)) == null ? defaultValue : v;
//        }
//
//        public void forEach(BiConsumer<? super K, ? super V> action) {
//            if (action == null)
//                throw new NullPointerException();
//            Node<K, V>[] t;
//            if ((t = table) != null) {
//                Traverser<K, V> it = new Traverser<K, V>(t, t.length, 0, t.length);
//                for (Node<K, V> p; (p = it.advance()) != null; ) {
//                    action.accept(p.key, p.val);
//                }
//            }
//        }
//
//        public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {
//            if (function == null)
//                throw new NullPointerException();
//            Node<K, V>[] t;
//            if ((t = table) != null) {
//                Traverser<K, V> it = new Traverser<K, V>(t, t.length, 0, t.length);
//                for (Node<K, V> p; (p = it.advance()) != null; ) {
//                    V oldValue = p.val;
//                    for (K key = p.key; ; ) {
//                        V newValue = function.apply(key, oldValue);
//                        if (newValue == null)
//                            throw new NullPointerException();
//                        if (replaceNode(key, newValue, oldValue) != null || (oldValue = get(key)) == null)
//                            break;
//                    }
//                }
//            }
//        }
//
//        /**
//         * If the specified key is not already associated with a value,
//         * attempts to compute its value using the given mapping function
//         * and enters it into this map unless {@code null}.  The entire
//         * method invocation is performed atomically, so the function is
//         * applied at most once per key.  Some attempted update operations
//         * on this map by other threads may be blocked while computation
//         * is in progress, so the computation should be short and simple,
//         * and must not attempt to update any other mappings of this map.
//         *
//         * @param key             key with which the specified value is to be associated
//         * @param mappingFunction the function to compute a value
//         * @return the current (existing or computed) value associated with
//         * the specified key, or null if the computed value is null
//         * @throws NullPointerException  if the specified key or mappingFunction
//         *                               is null
//         * @throws IllegalStateException if the computation detectably
//         *                               attempts a recursive update to this map that would
//         *                               otherwise never complete
//         * @throws RuntimeException      or Error if the mappingFunction does so,
//         *                               in which case the mapping is left unestablished
//         */
//        public V computeIfAbsent(K key, Function<? super K, ? extends V> mappingFunction) {
//            if (key == null || mappingFunction == null)
//                throw new NullPointerException();
//            int h = spread(key.hashCode());
//            V val = null;
//            int binCount = 0;
//            for (Node<K, V>[] tab = table; ; ) {
//                Node<K, V> f;
//                int n, i, fh;
//                if (tab == null || (n = tab.length) == 0)
//                    tab = initTable();
//                else if ((f = tabAt(tab, i = (n - 1) & h)) == null) {
//                    Node<K, V> r = new ReservationNode<K, V>();
//                    synchronized (r) {
//                        if (casTabAt(tab, i, null, r)) {
//                            binCount = 1;
//                            Node<K, V> node = null;
//                            try {
//                                if ((val = mappingFunction.apply(key)) != null)
//                                    node = new Node<K, V>(h, key, val, null);
//                            } finally {
//                                setTabAt(tab, i, node);
//                            }
//                        }
//                    }
//                    if (binCount != 0)
//                        break;
//                } else if ((fh = f.hash) == MOVED)
//                    tab = helpTransfer(tab, f);
//                else {
//                    boolean added = false;
//                    synchronized (f) {
//                        if (tabAt(tab, i) == f) {
//                            if (fh >= 0) {
//                                binCount = 1;
//                                for (Node<K, V> e = f; ; ++binCount) {
//                                    K ek;
//                                    V ev;
//                                    if (e.hash == h && ((ek = e.key) == key || (ek != null && key.equals(ek)))) {
//                                        val = e.val;
//                                        break;
//                                    }
//                                    Node<K, V> pred = e;
//                                    if ((e = e.next) == null) {
//                                        if ((val = mappingFunction.apply(key)) != null) {
//                                            added = true;
//                                            pred.next = new Node<K, V>(h, key, val, null);
//                                        }
//                                        break;
//                                    }
//                                }
//                            } else if (f instanceof TreeBin) {
//                                binCount = 2;
//                                TreeBin<K, V> t = (TreeBin<K, V>) f;
//                                TreeNode<K, V> r, p;
//                                if ((r = t.root) != null && (p = r.findTreeNode(h, key, null)) != null)
//                                    val = p.val;
//                                else if ((val = mappingFunction.apply(key)) != null) {
//                                    added = true;
//                                    t.putTreeVal(h, key, val);
//                                }
//                            }
//                        }
//                    }
//                    if (binCount != 0) {
//                        if (binCount >= TREEIFY_THRESHOLD)
//                            treeifyBin(tab, i);
//                        if (!added)
//                            return val;
//                        break;
//                    }
//                }
//            }
//            if (val != null)
//                addCount(1L, binCount);
//            return val;
//        }
//
//        /**
//         * If the value for the specified key is present, attempts to
//         * compute a new mapping given the key and its current mapped
//         * value.  The entire method invocation is performed atomically.
//         * Some attempted update operations on this map by other threads
//         * may be blocked while computation is in progress, so the
//         * computation should be short and simple, and must not attempt to
//         * update any other mappings of this map.
//         *
//         * @param key               key with which a value may be associated
//         * @param remappingFunction the function to compute a value
//         * @return the new value associated with the specified key, or null if none
//         * @throws NullPointerException  if the specified key or remappingFunction
//         *                               is null
//         * @throws IllegalStateException if the computation detectably
//         *                               attempts a recursive update to this map that would
//         *                               otherwise never complete
//         * @throws RuntimeException      or Error if the remappingFunction does so,
//         *                               in which case the mapping is unchanged
//         */
//        public V computeIfPresent(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
//            if (key == null || remappingFunction == null)
//                throw new NullPointerException();
//            int h = spread(key.hashCode());
//            V val = null;
//            int delta = 0;
//            int binCount = 0;
//            for (Node<K, V>[] tab = table; ; ) {
//                Node<K, V> f;
//                int n, i, fh;
//                if (tab == null || (n = tab.length) == 0)
//                    tab = initTable();
//                else if ((f = tabAt(tab, i = (n - 1) & h)) == null)
//                    break;
//                else if ((fh = f.hash) == MOVED)
//                    tab = helpTransfer(tab, f);
//                else {
//                    synchronized (f) {
//                        if (tabAt(tab, i) == f) {
//                            if (fh >= 0) {
//                                binCount = 1;
//                                for (Node<K, V> e = f, pred = null; ; ++binCount) {
//                                    K ek;
//                                    if (e.hash == h && ((ek = e.key) == key || (ek != null && key.equals(ek)))) {
//                                        val = remappingFunction.apply(key, e.val);
//                                        if (val != null)
//                                            e.val = val;
//                                        else {
//                                            delta = -1;
//                                            Node<K, V> en = e.next;
//                                            if (pred != null)
//                                                pred.next = en;
//                                            else
//                                                setTabAt(tab, i, en);
//                                        }
//                                        break;
//                                    }
//                                    pred = e;
//                                    if ((e = e.next) == null)
//                                        break;
//                                }
//                            } else if (f instanceof TreeBin) {
//                                binCount = 2;
//                                TreeBin<K, V> t = (TreeBin<K, V>) f;
//                                TreeNode<K, V> r, p;
//                                if ((r = t.root) != null && (p = r.findTreeNode(h, key, null)) != null) {
//                                    val = remappingFunction.apply(key, p.val);
//                                    if (val != null)
//                                        p.val = val;
//                                    else {
//                                        delta = -1;
//                                        if (t.removeTreeNode(p))
//                                            setTabAt(tab, i, untreeify(t.first));
//                                    }
//                                }
//                            }
//                        }
//                    }
//                    if (binCount != 0)
//                        break;
//                }
//            }
//            if (delta != 0)
//                addCount((long) delta, binCount);
//            return val;
//        }
//
//        /**
//         * Attempts to compute a mapping for the specified key and its
//         * current mapped value (or {@code null} if there is no current
//         * mapping). The entire method invocation is performed atomically.
//         * Some attempted update operations on this map by other threads
//         * may be blocked while computation is in progress, so the
//         * computation should be short and simple, and must not attempt to
//         * update any other mappings of this Map.
//         *
//         * @param key               key with which the specified value is to be associated
//         * @param remappingFunction the function to compute a value
//         * @return the new value associated with the specified key, or null if none
//         * @throws NullPointerException  if the specified key or remappingFunction
//         *                               is null
//         * @throws IllegalStateException if the computation detectably
//         *                               attempts a recursive update to this map that would
//         *                               otherwise never complete
//         * @throws RuntimeException      or Error if the remappingFunction does so,
//         *                               in which case the mapping is unchanged
//         */
//        public V compute(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
//            if (key == null || remappingFunction == null)
//                throw new NullPointerException();
//            int h = spread(key.hashCode());
//            V val = null;
//            int delta = 0;
//            int binCount = 0;
//            for (Node<K, V>[] tab = table; ; ) {
//                Node<K, V> f;
//                int n, i, fh;
//                if (tab == null || (n = tab.length) == 0)
//                    tab = initTable();
//                else if ((f = tabAt(tab, i = (n - 1) & h)) == null) {
//                    Node<K, V> r = new ReservationNode<K, V>();
//                    synchronized (r) {
//                        if (casTabAt(tab, i, null, r)) {
//                            binCount = 1;
//                            Node<K, V> node = null;
//                            try {
//                                if ((val = remappingFunction.apply(key, null)) != null) {
//                                    delta = 1;
//                                    node = new Node<K, V>(h, key, val, null);
//                                }
//                            } finally {
//                                setTabAt(tab, i, node);
//                            }
//                        }
//                    }
//                    if (binCount != 0)
//                        break;
//                } else if ((fh = f.hash) == MOVED)
//                    tab = helpTransfer(tab, f);
//                else {
//                    synchronized (f) {
//                        if (tabAt(tab, i) == f) {
//                            if (fh >= 0) {
//                                binCount = 1;
//                                for (Node<K, V> e = f, pred = null; ; ++binCount) {
//                                    K ek;
//                                    if (e.hash == h && ((ek = e.key) == key || (ek != null && key.equals(ek)))) {
//                                        val = remappingFunction.apply(key, e.val);
//                                        if (val != null)
//                                            e.val = val;
//                                        else {
//                                            delta = -1;
//                                            Node<K, V> en = e.next;
//                                            if (pred != null)
//                                                pred.next = en;
//                                            else
//                                                setTabAt(tab, i, en);
//                                        }
//                                        break;
//                                    }
//                                    pred = e;
//                                    if ((e = e.next) == null) {
//                                        val = remappingFunction.apply(key, null);
//                                        if (val != null) {
//                                            delta = 1;
//                                            pred.next = new Node<K, V>(h, key, val, null);
//                                        }
//                                        break;
//                                    }
//                                }
//                            } else if (f instanceof TreeBin) {
//                                binCount = 1;
//                                TreeBin<K, V> t = (TreeBin<K, V>) f;
//                                TreeNode<K, V> r, p;
//                                if ((r = t.root) != null)
//                                    p = r.findTreeNode(h, key, null);
//                                else
//                                    p = null;
//                                V pv = (p == null) ? null : p.val;
//                                val = remappingFunction.apply(key, pv);
//                                if (val != null) {
//                                    if (p != null)
//                                        p.val = val;
//                                    else {
//                                        delta = 1;
//                                        t.putTreeVal(h, key, val);
//                                    }
//                                } else if (p != null) {
//                                    delta = -1;
//                                    if (t.removeTreeNode(p))
//                                        setTabAt(tab, i, untreeify(t.first));
//                                }
//                            }
//                        }
//                    }
//                    if (binCount != 0) {
//                        if (binCount >= TREEIFY_THRESHOLD)
//                            treeifyBin(tab, i);
//                        break;
//                    }
//                }
//            }
//            if (delta != 0)
//                addCount((long) delta, binCount);
//            return val;
//        }
//
//        /**
//         * If the specified key is not already associated with a
//         * (non-null) value, associates it with the given value.
//         * Otherwise, replaces the value with the results of the given
//         * remapping function, or removes if {@code null}. The entire
//         * method invocation is performed atomically.  Some attempted
//         * update operations on this map by other threads may be blocked
//         * while computation is in progress, so the computation should be
//         * short and simple, and must not attempt to update any other
//         * mappings of this Map.
//         *
//         * @param key               key with which the specified value is to be associated
//         * @param value             the value to use if absent
//         * @param remappingFunction the function to recompute a value if present
//         * @return the new value associated with the specified key, or null if none
//         * @throws NullPointerException if the specified key or the
//         *                              remappingFunction is null
//         * @throws RuntimeException     or Error if the remappingFunction does so,
//         *                              in which case the mapping is unchanged
//         */
//        public V merge(K key, V value, BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
//            if (key == null || value == null || remappingFunction == null)
//                throw new NullPointerException();
//            int h = spread(key.hashCode());
//            V val = null;
//            int delta = 0;
//            int binCount = 0;
//            for (Node<K, V>[] tab = table; ; ) {
//                Node<K, V> f;
//                int n, i, fh;
//                if (tab == null || (n = tab.length) == 0)
//                    tab = initTable();
//                else if ((f = tabAt(tab, i = (n - 1) & h)) == null) {
//                    if (casTabAt(tab, i, null, new Node<K, V>(h, key, value, null))) {
//                        delta = 1;
//                        val = value;
//                        break;
//                    }
//                } else if ((fh = f.hash) == MOVED)
//                    tab = helpTransfer(tab, f);
//                else {
//                    synchronized (f) {
//                        if (tabAt(tab, i) == f) {
//                            if (fh >= 0) {
//                                binCount = 1;
//                                for (Node<K, V> e = f, pred = null; ; ++binCount) {
//                                    K ek;
//                                    if (e.hash == h && ((ek = e.key) == key || (ek != null && key.equals(ek)))) {
//                                        val = remappingFunction.apply(e.val, value);
//                                        if (val != null)
//                                            e.val = val;
//                                        else {
//                                            delta = -1;
//                                            Node<K, V> en = e.next;
//                                            if (pred != null)
//                                                pred.next = en;
//                                            else
//                                                setTabAt(tab, i, en);
//                                        }
//                                        break;
//                                    }
//                                    pred = e;
//                                    if ((e = e.next) == null) {
//                                        delta = 1;
//                                        val = value;
//                                        pred.next = new Node<K, V>(h, key, val, null);
//                                        break;
//                                    }
//                                }
//                            } else if (f instanceof TreeBin) {
//                                binCount = 2;
//                                TreeBin<K, V> t = (TreeBin<K, V>) f;
//                                TreeNode<K, V> r = t.root;
//                                TreeNode<K, V> p = (r == null) ? null : r.findTreeNode(h, key, null);
//                                val = (p == null) ? value : remappingFunction.apply(p.val, value);
//                                if (val != null) {
//                                    if (p != null)
//                                        p.val = val;
//                                    else {
//                                        delta = 1;
//                                        t.putTreeVal(h, key, val);
//                                    }
//                                } else if (p != null) {
//                                    delta = -1;
//                                    if (t.removeTreeNode(p))
//                                        setTabAt(tab, i, untreeify(t.first));
//                                }
//                            }
//                        }
//                    }
//                    if (binCount != 0) {
//                        if (binCount >= TREEIFY_THRESHOLD)
//                            treeifyBin(tab, i);
//                        break;
//                    }
//                }
//            }
//            if (delta != 0)
//                addCount((long) delta, binCount);
//            return val;
//        }
//
//        // Hashtable legacy methods
//
//        /**
//         * Legacy method testing if some key maps into the specified value
//         * in this table.  This method is identical in functionality to
//         * {@link #containsValue(Object)}, and exists solely to ensure
//         * full compatibility with class {@link java.util.Hashtable},
//         * which supported this method prior to introduction of the
//         * Java Collections framework.
//         *
//         * @param value a value to search for
//         * @return {@code true} if and only if some key maps to the
//         * {@code value} argument in this table as
//         * determined by the {@code equals} method;
//         * {@code false} otherwise
//         * @throws NullPointerException if the specified value is null
//         */
//        public boolean contains(Object value) {
//            return containsValue(value);
//        }
//
//        /**
//         * Returns an enumeration of the keys in this table.
//         *
//         * @return an enumeration of the keys in this table
//         * @see #keySet()
//         */
//        public Enumeration<K> keys() {
//            Node<K, V>[] t;
//            int f = (t = table) == null ? 0 : t.length;
//            return new KeyIterator<K, V>(t, f, 0, f, this);
//        }
//
//        /**
//         * Returns an enumeration of the values in this table.
//         *
//         * @return an enumeration of the values in this table
//         * @see #values()
//         */
//        public Enumeration<V> elements() {
//            Node<K, V>[] t;
//            int f = (t = table) == null ? 0 : t.length;
//            return new ValueIterator<K, V>(t, f, 0, f, this);
//        }
//
//        // ConcurrentHashMap-only methods
//
//        /**
//         * Returns the number of mappings. This method should be used
//         * instead of {@link #size} because a ConcurrentHashMap may
//         * contain more mappings than can be represented as an int. The
//         * value returned is an estimate; the actual count may differ if
//         * there are concurrent insertions or removals.
//         *
//         * @return the number of mappings
//         * @since 1.8
//         */
//        public long mappingCount() {
//            long n = sumCount();
//            return (n < 0L) ? 0L : n; // ignore transient negative values
//        }
//
//        /**
//         * Creates a new {@link Set} backed by a ConcurrentHashMap
//         * from the given type to {@code Boolean.TRUE}.
//         *
//         * @param <K> the element type of the returned set
//         * @return the new set
//         * @since 1.8
//         */
//        public static <K> KeySetView<K, Boolean> newKeySet() {
//            return new KeySetView<K, Boolean>(new ConcurrentHashMap<K, Boolean>(), Boolean.TRUE);
//        }
//
//        /**
//         * Creates a new {@link Set} backed by a ConcurrentHashMap
//         * from the given type to {@code Boolean.TRUE}.
//         *
//         * @param initialCapacity The implementation performs internal
//         *                        sizing to accommodate this many elements.
//         * @param <K>             the element type of the returned set
//         * @return the new set
//         * @throws IllegalArgumentException if the initial capacity of
//         *                                  elements is negative
//         * @since 1.8
//         */
//        public static <K> KeySetView<K, Boolean> newKeySet(int initialCapacity) {
//            return new KeySetView<K, Boolean>(new ConcurrentHashMap<K, Boolean>(initialCapacity), Boolean.TRUE);
//        }
//
//        /**
//         * Returns a {@link Set} view of the keys in this map, using the
//         * given common mapped value for any additions (i.e., {@link
//         * Collection#add} and {@link Collection#addAll(Collection)}).
//         * This is of course only appropriate if it is acceptable to use
//         * the same value for all additions from this view.
//         *
//         * @param mappedValue the mapped value to use for any additions
//         * @return the set view
//         * @throws NullPointerException if the mappedValue is null
//         */
//        public KeySetView<K, V> keySet(V mappedValue) {
//            if (mappedValue == null)
//                throw new NullPointerException();
//            return new KeySetView<K, V>(this, mappedValue);
//        }
//
//    /* ---------------- Special Nodes -------------- */
//
//        /**
//         * A node inserted at head of bins during transfer operations.
//         */
//        static final class ForwardingNode<K, V> extends Node<K, V> {
//            final Node<K, V>[] nextTable;
//
//            ForwardingNode(Node<K, V>[] tab) {
//                super(MOVED, null, null, null);
//                this.nextTable = tab;
//            }
//
//            Node<K, V> find(int h, Object k) {
//                // loop to avoid arbitrarily deep recursion on forwarding nodes
//                outer:
//                for (Node<K, V>[] tab = nextTable; ; ) {
//                    Node<K, V> e;
//                    int n;
//                    if (k == null || tab == null || (n = tab.length) == 0 || (e = tabAt(tab, (n - 1) & h)) == null)
//                        return null;
//                    for (; ; ) {
//                        int eh;
//                        K ek;
//                        if ((eh = e.hash) == h && ((ek = e.key) == k || (ek != null && k.equals(ek))))
//                            return e;
//                        if (eh < 0) {
//                            if (e instanceof ForwardingNode) {
//                                tab = ((ForwardingNode<K, V>) e).nextTable;
//                                continue outer;
//                            } else
//                                return e.find(h, k);
//                        }
//                        if ((e = e.next) == null)
//                            return null;
//                    }
//                }
//            }
//        }
//
//        /**
//         * A place-holder node used in computeIfAbsent and compute
//         */
//        static final class ReservationNode<K, V> extends Node<K, V> {
//            ReservationNode() {
//                super(RESERVED, null, null, null);
//            }
//
//            Node<K, V> find(int h, Object k) {
//                return null;
//            }
//        }
//
//    /* ---------------- Table Initialization and Resizing -------------- */
//
//        /**
//         * Returns the stamp bits for resizing a table of size n.
//         * Must be negative when shifted left by RESIZE_STAMP_SHIFT.
//         */
//        static final int resizeStamp(int n) {
//            return Integer.numberOfLeadingZeros(n) | (1 << (RESIZE_STAMP_BITS - 1));
//        }
//
//        /**
//         * Initializes table, using the size recorded in sizeCtl.
//         */
//        private final Node<K, V>[] initTable() {
//            Node<K, V>[] tab;
//            int sc;
//            while ((tab = table) == null || tab.length == 0) {
//                if ((sc = sizeCtl) < 0)
//                    Thread.yield(); // lost initialization race; just spin
//                else if (U.compareAndSwapInt(this, SIZECTL, sc, -1)) {
//                    try {
//                        if ((tab = table) == null || tab.length == 0) {
//                            int n = (sc > 0) ? sc : DEFAULT_CAPACITY;
//                            @SuppressWarnings("unchecked") Node<K, V>[] nt = (Node<K, V>[]) new Node<?, ?>[n];
//                            table = tab = nt;
//                            sc = n - (n >>> 2);
//                        }
//                    } finally {
//                        sizeCtl = sc;
//                    }
//                    break;
//                }
//            }
//            return tab;
//        }
//
//        /**
//         * Adds to count, and if table is too small and not already
//         * resizing, initiates transfer. If already resizing, helps
//         * perform transfer if work is available.  Rechecks occupancy
//         * after a transfer to see if another resize is already needed
//         * because resizings are lagging additions.
//         *
//         * @param x     the count to add
//         * @param check if <0, don't check resize, if <= 1 only check if uncontended
//         */
//        private final void addCount(long x, int check) {
//            CounterCell[] as;
//            long b, s;
//            if ((as = counterCells) != null || !U.compareAndSwapLong(this, BASECOUNT, b = baseCount, s = b + x)) {
//                CounterCell a;
//                long v;
//                int m;
//                boolean uncontended = true;
//                if (as == null || (m = as.length - 1) < 0 || (a = as[ThreadLocalRandom.getProbe() & m]) == null || !(uncontended = U.compareAndSwapLong(a, CELLVALUE, v = a.value, v + x))) {
//                    fullAddCount(x, uncontended);
//                    return;
//                }
//                if (check <= 1)
//                    return;
//                s = sumCount();
//            }
//            if (check >= 0) {
//                Node<K, V>[] tab, nt;
//                int n, sc;
//                while (s >= (long) (sc = sizeCtl) && (tab = table) != null && (n = tab.length) < MAXIMUM_CAPACITY) {
//                    int rs = resizeStamp(n);
//                    if (sc < 0) {
//                        if ((sc >>> RESIZE_STAMP_SHIFT) != rs || sc == rs + 1 || sc == rs + MAX_RESIZERS || (nt = nextTable) == null || transferIndex <= 0)
//                            break;
//                        if (U.compareAndSwapInt(this, SIZECTL, sc, sc + 1))
//                            transfer(tab, nt);
//                    } else if (U.compareAndSwapInt(this, SIZECTL, sc, (rs << RESIZE_STAMP_SHIFT) + 2))
//                        transfer(tab, null);
//                    s = sumCount();
//                }
//            }
//        }
//
//        /**
//         * Helps transfer if a resize is in progress.
//         */
//        final Node<K, V>[] helpTransfer(Node<K, V>[] tab, Node<K, V> f) {
//            Node<K, V>[] nextTab;
//            int sc;
//            if (tab != null && (f instanceof ForwardingNode) && (nextTab = ((ForwardingNode<K, V>) f).nextTable) != null) {
//                int rs = resizeStamp(tab.length);
//                while (nextTab == nextTable && table == tab && (sc = sizeCtl) < 0) {
//                    if ((sc >>> RESIZE_STAMP_SHIFT) != rs || sc == rs + 1 || sc == rs + MAX_RESIZERS || transferIndex <= 0)
//                        break;
//                    if (U.compareAndSwapInt(this, SIZECTL, sc, sc + 1)) {
//                        transfer(tab, nextTab);
//                        break;
//                    }
//                }
//                return nextTab;
//            }
//            return table;
//        }
//
//        /**
//         * Tries to presize table to accommodate the given number of elements.
//         *
//         * @param size number of elements (doesn't need to be perfectly accurate)
//         */
//        private final void tryPresize(int size) {
//            int c = (size >= (MAXIMUM_CAPACITY >>> 1)) ? MAXIMUM_CAPACITY : tableSizeFor(size + (size >>> 1) + 1);
//            int sc;
//            while ((sc = sizeCtl) >= 0) {
//                Node<K, V>[] tab = table;
//                int n;
//                if (tab == null || (n = tab.length) == 0) {
//                    n = (sc > c) ? sc : c;
//                    if (U.compareAndSwapInt(this, SIZECTL, sc, -1)) {
//                        try {
//                            if (table == tab) {
//                                @SuppressWarnings("unchecked") Node<K, V>[] nt = (Node<K, V>[]) new Node<?, ?>[n];
//                                table = nt;
//                                sc = n - (n >>> 2);
//                            }
//                        } finally {
//                            sizeCtl = sc;
//                        }
//                    }
//                } else if (c <= sc || n >= MAXIMUM_CAPACITY)
//                    break;
//                else if (tab == table) {
//                    int rs = resizeStamp(n);
//                    if (sc < 0) {
//                        Node<K, V>[] nt;
//                        if ((sc >>> RESIZE_STAMP_SHIFT) != rs || sc == rs + 1 || sc == rs + MAX_RESIZERS || (nt = nextTable) == null || transferIndex <= 0)
//                            break;
//                        if (U.compareAndSwapInt(this, SIZECTL, sc, sc + 1))
//                            transfer(tab, nt);
//                    } else if (U.compareAndSwapInt(this, SIZECTL, sc, (rs << RESIZE_STAMP_SHIFT) + 2))
//                        transfer(tab, null);
//                }
//            }
//        }
//
//        /**
//         * Moves and/or copies the nodes in each bin to new table. See
//         * above for explanation.
//         */
//        private final void transfer(Node<K, V>[] tab, Node<K, V>[] nextTab) {
//            int n = tab.length, stride;
//            if ((stride = (NCPU > 1) ? (n >>> 3) / NCPU : n) < MIN_TRANSFER_STRIDE)
//                stride = MIN_TRANSFER_STRIDE; // subdivide range
//            if (nextTab == null) {            // initiating
//                try {
//                    @SuppressWarnings("unchecked") Node<K, V>[] nt = (Node<K, V>[]) new Node<?, ?>[n << 1];
//                    nextTab = nt;
//                } catch (Throwable ex) {      // try to cope with OOME
//                    sizeCtl = Integer.MAX_VALUE;
//                    return;
//                }
//                nextTable = nextTab;
//                transferIndex = n;
//            }
//            int nextn = nextTab.length;
//            ForwardingNode<K, V> fwd = new ForwardingNode<K, V>(nextTab);
//            boolean advance = true;
//            boolean finishing = false; // to ensure sweep before committing nextTab
//            for (int i = 0, bound = 0; ; ) {
//                Node<K, V> f;
//                int fh;
//                while (advance) {
//                    int nextIndex, nextBound;
//                    if (--i >= bound || finishing)
//                        advance = false;
//                    else if ((nextIndex = transferIndex) <= 0) {
//                        i = -1;
//                        advance = false;
//                    } else if (U.compareAndSwapInt(this, TRANSFERINDEX, nextIndex, nextBound = (nextIndex > stride ? nextIndex - stride : 0))) {
//                        bound = nextBound;
//                        i = nextIndex - 1;
//                        advance = false;
//                    }
//                }
//                if (i < 0 || i >= n || i + n >= nextn) {
//                    int sc;
//                    if (finishing) {
//                        nextTable = null;
//                        table = nextTab;
//                        sizeCtl = (n << 1) - (n >>> 1);
//                        return;
//                    }
//                    if (U.compareAndSwapInt(this, SIZECTL, sc = sizeCtl, sc - 1)) {
//                        if ((sc - 2) != resizeStamp(n) << RESIZE_STAMP_SHIFT)
//                            return;
//                        finishing = advance = true;
//                        i = n; // recheck before commit
//                    }
//                } else if ((f = tabAt(tab, i)) == null)
//                    advance = casTabAt(tab, i, null, fwd);
//                else if ((fh = f.hash) == MOVED)
//                    advance = true; // already processed
//                else {
//                    synchronized (f) {
//                        if (tabAt(tab, i) == f) {
//                            Node<K, V> ln, hn;
//                            if (fh >= 0) {
//                                int runBit = fh & n;
//                                Node<K, V> lastRun = f;
//                                for (Node<K, V> p = f.next; p != null; p = p.next) {
//                                    int b = p.hash & n;
//                                    if (b != runBit) {
//                                        runBit = b;
//                                        lastRun = p;
//                                    }
//                                }
//                                if (runBit == 0) {
//                                    ln = lastRun;
//                                    hn = null;
//                                } else {
//                                    hn = lastRun;
//                                    ln = null;
//                                }
//                                for (Node<K, V> p = f; p != lastRun; p = p.next) {
//                                    int ph = p.hash;
//                                    K pk = p.key;
//                                    V pv = p.val;
//                                    if ((ph & n) == 0)
//                                        ln = new Node<K, V>(ph, pk, pv, ln);
//                                    else
//                                        hn = new Node<K, V>(ph, pk, pv, hn);
//                                }
//                                setTabAt(nextTab, i, ln);
//                                setTabAt(nextTab, i + n, hn);
//                                setTabAt(tab, i, fwd);
//                                advance = true;
//                            } else if (f instanceof TreeBin) {
//                                TreeBin<K, V> t = (TreeBin<K, V>) f;
//                                TreeNode<K, V> lo = null, loTail = null;
//                                TreeNode<K, V> hi = null, hiTail = null;
//                                int lc = 0, hc = 0;
//                                for (Node<K, V> e = t.first; e != null; e = e.next) {
//                                    int h = e.hash;
//                                    TreeNode<K, V> p = new TreeNode<K, V>(h, e.key, e.val, null, null);
//                                    if ((h & n) == 0) {
//                                        if ((p.prev = loTail) == null)
//                                            lo = p;
//                                        else
//                                            loTail.next = p;
//                                        loTail = p;
//                                        ++lc;
//                                    } else {
//                                        if ((p.prev = hiTail) == null)
//                                            hi = p;
//                                        else
//                                            hiTail.next = p;
//                                        hiTail = p;
//                                        ++hc;
//                                    }
//                                }
//                                ln = (lc <= UNTREEIFY_THRESHOLD) ? untreeify(lo) : (hc != 0) ? new TreeBin<K, V>(lo) : t;
//                                hn = (hc <= UNTREEIFY_THRESHOLD) ? untreeify(hi) : (lc != 0) ? new TreeBin<K, V>(hi) : t;
//                                setTabAt(nextTab, i, ln);
//                                setTabAt(nextTab, i + n, hn);
//                                setTabAt(tab, i, fwd);
//                                advance = true;
//                            }
//                        }
//                    }
//                }
//            }
//        }
//
//    /* ---------------- Counter support -------------- */
//
//        /**
//         * A padded cell for distributing counts.  Adapted from LongAdder
//         * and Striped64.  See their internal docs for explanation.
//         */
//        @sun.misc.Contended
//        static final class CounterCell {
//            volatile long value;
//
//            CounterCell(long x) {
//                value = x;
//            }
//        }
//
//        final long sumCount() {
//            CounterCell[] as = counterCells;
//            CounterCell a;
//            long sum = baseCount;
//            if (as != null) {
//                for (int i = 0; i < as.length; ++i) {
//                    if ((a = as[i]) != null)
//                        sum += a.value;
//                }
//            }
//            return sum;
//        }
//
//        // See LongAdder version for explanation
//        private final void fullAddCount(long x, boolean wasUncontended) {
//            int h;
//            if ((h = ThreadLocalRandom.getProbe()) == 0) {
//                ThreadLocalRandom.localInit();      // force initialization
//                h = ThreadLocalRandom.getProbe();
//                wasUncontended = true;
//            }
//            boolean collide = false;                // True if last slot nonempty
//            for (; ; ) {
//                CounterCell[] as;
//                CounterCell a;
//                int n;
//                long v;
//                if ((as = counterCells) != null && (n = as.length) > 0) {
//                    if ((a = as[(n - 1) & h]) == null) {
//                        if (cellsBusy == 0) {            // Try to attach new Cell
//                            CounterCell r = new CounterCell(x); // Optimistic create
//                            if (cellsBusy == 0 && U.compareAndSwapInt(this, CELLSBUSY, 0, 1)) {
//                                boolean created = false;
//                                try {               // Recheck under lock
//                                    CounterCell[] rs;
//                                    int m, j;
//                                    if ((rs = counterCells) != null && (m = rs.length) > 0 && rs[j = (m - 1) & h] == null) {
//                                        rs[j] = r;
//                                        created = true;
//                                    }
//                                } finally {
//                                    cellsBusy = 0;
//                                }
//                                if (created)
//                                    break;
//                                continue;           // Slot is now non-empty
//                            }
//                        }
//                        collide = false;
//                    } else if (!wasUncontended)       // CAS already known to fail
//                        wasUncontended = true;      // Continue after rehash
//                    else if (U.compareAndSwapLong(a, CELLVALUE, v = a.value, v + x))
//                        break;
//                    else if (counterCells != as || n >= NCPU)
//                        collide = false;            // At max size or stale
//                    else if (!collide)
//                        collide = true;
//                    else if (cellsBusy == 0 && U.compareAndSwapInt(this, CELLSBUSY, 0, 1)) {
//                        try {
//                            if (counterCells == as) {// Expand table unless stale
//                                CounterCell[] rs = new CounterCell[n << 1];
//                                for (int i = 0; i < n; ++i)
//                                    rs[i] = as[i];
//                                counterCells = rs;
//                            }
//                        } finally {
//                            cellsBusy = 0;
//                        }
//                        collide = false;
//                        continue;                   // Retry with expanded table
//                    }
//                    h = ThreadLocalRandom.advanceProbe(h);
//                } else if (cellsBusy == 0 && counterCells == as && U.compareAndSwapInt(this, CELLSBUSY, 0, 1)) {
//                    boolean init = false;
//                    try {                           // Initialize table
//                        if (counterCells == as) {
//                            CounterCell[] rs = new CounterCell[2];
//                            rs[h & 1] = new CounterCell(x);
//                            counterCells = rs;
//                            init = true;
//                        }
//                    } finally {
//                        cellsBusy = 0;
//                    }
//                    if (init)
//                        break;
//                } else if (U.compareAndSwapLong(this, BASECOUNT, v = baseCount, v + x))
//                    break;                          // Fall back on using base
//            }
//        }
//
//    /* ---------------- Conversion from/to TreeBins -------------- */
//
//        /**
//         * Replaces all linked nodes in bin at given index unless table is
//         * too small, in which case resizes instead.
//         */
//        private final void treeifyBin(Node<K, V>[] tab, int index) {
//            Node<K, V> b;
//            int n, sc;
//            if (tab != null) {
//                if ((n = tab.length) < MIN_TREEIFY_CAPACITY)
//                    tryPresize(n << 1);
//                else if ((b = tabAt(tab, index)) != null && b.hash >= 0) {
//                    synchronized (b) {
//                        if (tabAt(tab, index) == b) {
//                            TreeNode<K, V> hd = null, tl = null;
//                            for (Node<K, V> e = b; e != null; e = e.next) {
//                                TreeNode<K, V> p = new TreeNode<K, V>(e.hash, e.key, e.val, null, null);
//                                if ((p.prev = tl) == null)
//                                    hd = p;
//                                else
//                                    tl.next = p;
//                                tl = p;
//                            }
//                            setTabAt(tab, index, new TreeBin<K, V>(hd));
//                        }
//                    }
//                }
//            }
//        }
//
//        /**
//         * Returns a list on non-TreeNodes replacing those in given list.
//         */
//        static <K, V> Node<K, V> untreeify(Node<K, V> b) {
//            Node<K, V> hd = null, tl = null;
//            for (Node<K, V> q = b; q != null; q = q.next) {
//                Node<K, V> p = new Node<K, V>(q.hash, q.key, q.val, null);
//                if (tl == null)
//                    hd = p;
//                else
//                    tl.next = p;
//                tl = p;
//            }
//            return hd;
//        }
//
//    /* ---------------- TreeNodes -------------- */
//
//        /**
//         * Nodes for use in TreeBins
//         */
//        static final class TreeNode<K, V> extends Node<K, V> {
//            TreeNode<K, V> parent;  // red-black tree links
//            TreeNode<K, V> left;
//            TreeNode<K, V> right;
//            TreeNode<K, V> prev;    // needed to unlink next upon deletion
//            boolean red;
//
//            TreeNode(int hash, K key, V val, Node<K, V> next, TreeNode<K, V> parent) {
//                super(hash, key, val, next);
//                this.parent = parent;
//            }
//
//            Node<K, V> find(int h, Object k) {
//                return findTreeNode(h, k, null);
//            }
//
//            /**
//             * Returns the TreeNode (or null if not found) for the given key
//             * starting at given root.
//             */
//            final TreeNode<K, V> findTreeNode(int h, Object k, Class<?> kc) {
//                if (k != null) {
//                    TreeNode<K, V> p = this;
//                    do {
//                        int ph, dir;
//                        K pk;
//                        TreeNode<K, V> q;
//                        TreeNode<K, V> pl = p.left, pr = p.right;
//                        if ((ph = p.hash) > h)
//                            p = pl;
//                        else if (ph < h)
//                            p = pr;
//                        else if ((pk = p.key) == k || (pk != null && k.equals(pk)))
//                            return p;
//                        else if (pl == null)
//                            p = pr;
//                        else if (pr == null)
//                            p = pl;
//                        else if ((kc != null || (kc = comparableClassFor(k)) != null) && (dir = compareComparables(kc, k, pk)) != 0)
//                            p = (dir < 0) ? pl : pr;
//                        else if ((q = pr.findTreeNode(h, k, kc)) != null)
//                            return q;
//                        else
//                            p = pl;
//                    } while (p != null);
//                }
//                return null;
//            }
//        }
//
//    /* ---------------- TreeBins -------------- */
//
//        /**
//         * TreeNodes used at the heads of bins. TreeBins do not hold user
//         * keys or values, but instead point to list of TreeNodes and
//         * their root. They also maintain a parasitic read-write lock
//         * forcing writers (who hold bin lock) to wait for readers (who do
//         * not) to complete before tree restructuring operations.
//         */
//        static final class TreeBin<K, V> extends Node<K, V> {
//            TreeNode<K, V> root;
//            volatile TreeNode<K, V> first;
//            volatile Thread waiter;
//            volatile int lockState;
//            // values for lockState
//            static final int WRITER = 1; // set while holding write lock
//            static final int WAITER = 2; // set when waiting for write lock
//            static final int READER = 4; // increment value for setting read lock
//
//            /**
//             * Tie-breaking utility for ordering insertions when equal
//             * hashCodes and non-comparable. We don't require a total
//             * order, just a consistent insertion rule to maintain
//             * equivalence across rebalancings. Tie-breaking further than
//             * necessary simplifies testing a bit.
//             */
//            static int tieBreakOrder(Object a, Object b) {
//                int d;
//                if (a == null || b == null || (d = a.getClass().getName().
//                        compareTo(b.getClass().getName())) == 0)
//                    d = (System.identityHashCode(a) <= System.identityHashCode(b) ? -1 : 1);
//                return d;
//            }
//
//            /**
//             * Creates bin with initial set of nodes headed by b.
//             */
//            TreeBin(TreeNode<K, V> b) {
//                super(TREEBIN, null, null, null);
//                this.first = b;
//                TreeNode<K, V> r = null;
//                for (TreeNode<K, V> x = b, next; x != null; x = next) {
//                    next = (TreeNode<K, V>) x.next;
//                    x.left = x.right = null;
//                    if (r == null) {
//                        x.parent = null;
//                        x.red = false;
//                        r = x;
//                    } else {
//                        K k = x.key;
//                        int h = x.hash;
//                        Class<?> kc = null;
//                        for (TreeNode<K, V> p = r; ; ) {
//                            int dir, ph;
//                            K pk = p.key;
//                            if ((ph = p.hash) > h)
//                                dir = -1;
//                            else if (ph < h)
//                                dir = 1;
//                            else if ((kc == null && (kc = comparableClassFor(k)) == null) || (dir = compareComparables(kc, k, pk)) == 0)
//                                dir = tieBreakOrder(k, pk);
//                            TreeNode<K, V> xp = p;
//                            if ((p = (dir <= 0) ? p.left : p.right) == null) {
//                                x.parent = xp;
//                                if (dir <= 0)
//                                    xp.left = x;
//                                else
//                                    xp.right = x;
//                                r = balanceInsertion(r, x);
//                                break;
//                            }
//                        }
//                    }
//                }
//                this.root = r;
//                assert checkInvariants(root);
//            }
//
//            /**
//             * Acquires write lock for tree restructuring.
//             */
//            private final void lockRoot() {
//                if (!U.compareAndSwapInt(this, LOCKSTATE, 0, WRITER))
//                    contendedLock(); // offload to separate method
//            }
//
//            /**
//             * Releases write lock for tree restructuring.
//             */
//            private final void unlockRoot() {
//                lockState = 0;
//            }
//
//            /**
//             * Possibly blocks awaiting root lock.
//             */
//            private final void contendedLock() {
//                boolean waiting = false;
//                for (int s; ; ) {
//                    if (((s = lockState) & ~WAITER) == 0) {
//                        if (U.compareAndSwapInt(this, LOCKSTATE, s, WRITER)) {
//                            if (waiting)
//                                waiter = null;
//                            return;
//                        }
//                    } else if ((s & WAITER) == 0) {
//                        if (U.compareAndSwapInt(this, LOCKSTATE, s, s | WAITER)) {
//                            waiting = true;
//                            waiter = Thread.currentThread();
//                        }
//                    } else if (waiting)
//                        LockSupport.park(this);
//                }
//            }
//
//            /**
//             * Returns matching node or null if none. Tries to search
//             * using tree comparisons from root, but continues linear
//             * search when lock not available.
//             */
//            final Node<K, V> find(int h, Object k) {
//                if (k != null) {
//                    for (Node<K, V> e = first; e != null; ) {
//                        int s;
//                        K ek;
//                        if (((s = lockState) & (WAITER | WRITER)) != 0) {
//                            if (e.hash == h && ((ek = e.key) == k || (ek != null && k.equals(ek))))
//                                return e;
//                            e = e.next;
//                        } else if (U.compareAndSwapInt(this, LOCKSTATE, s, s + READER)) {
//                            TreeNode<K, V> r, p;
//                            try {
//                                p = ((r = root) == null ? null : r.findTreeNode(h, k, null));
//                            } finally {
//                                Thread w;
//                                if (U.getAndAddInt(this, LOCKSTATE, -READER) == (READER | WAITER) && (w = waiter) != null)
//                                    LockSupport.unpark(w);
//                            }
//                            return p;
//                        }
//                    }
//                }
//                return null;
//            }
//
//            /**
//             * Finds or adds a node.
//             *
//             * @return null if added
//             */
//            final TreeNode<K, V> putTreeVal(int h, K k, V v) {
//                Class<?> kc = null;
//                boolean searched = false;
//                for (TreeNode<K, V> p = root; ; ) {
//                    int dir, ph;
//                    K pk;
//                    if (p == null) {
//                        first = root = new TreeNode<K, V>(h, k, v, null, null);
//                        break;
//                    } else if ((ph = p.hash) > h)
//                        dir = -1;
//                    else if (ph < h)
//                        dir = 1;
//                    else if ((pk = p.key) == k || (pk != null && k.equals(pk)))
//                        return p;
//                    else if ((kc == null && (kc = comparableClassFor(k)) == null) || (dir = compareComparables(kc, k, pk)) == 0) {
//                        if (!searched) {
//                            TreeNode<K, V> q, ch;
//                            searched = true;
//                            if (((ch = p.left) != null && (q = ch.findTreeNode(h, k, kc)) != null) || ((ch = p.right) != null && (q = ch.findTreeNode(h, k, kc)) != null))
//                                return q;
//                        }
//                        dir = tieBreakOrder(k, pk);
//                    }
//
//                    TreeNode<K, V> xp = p;
//                    if ((p = (dir <= 0) ? p.left : p.right) == null) {
//                        TreeNode<K, V> x, f = first;
//                        first = x = new TreeNode<K, V>(h, k, v, f, xp);
//                        if (f != null)
//                            f.prev = x;
//                        if (dir <= 0)
//                            xp.left = x;
//                        else
//                            xp.right = x;
//                        if (!xp.red)
//                            x.red = true;
//                        else {
//                            lockRoot();
//                            try {
//                                root = balanceInsertion(root, x);
//                            } finally {
//                                unlockRoot();
//                            }
//                        }
//                        break;
//                    }
//                }
//                assert checkInvariants(root);
//                return null;
//            }
//
//            /**
//             * Removes the given node, that must be present before this
//             * call.  This is messier than typical red-black deletion code
//             * because we cannot swap the contents of an interior node
//             * with a leaf successor that is pinned by "next" pointers
//             * that are accessible independently of lock. So instead we
//             * swap the tree linkages.
//             *
//             * @return true if now too small, so should be untreeified
//             */
//            final boolean removeTreeNode(TreeNode<K, V> p) {
//                TreeNode<K, V> next = (TreeNode<K, V>) p.next;
//                TreeNode<K, V> pred = p.prev;  // unlink traversal pointers
//                TreeNode<K, V> r, rl;
//                if (pred == null)
//                    first = next;
//                else
//                    pred.next = next;
//                if (next != null)
//                    next.prev = pred;
//                if (first == null) {
//                    root = null;
//                    return true;
//                }
//                if ((r = root) == null || r.right == null || // too small
//                        (rl = r.left) == null || rl.left == null)
//                    return true;
//                lockRoot();
//                try {
//                    TreeNode<K, V> replacement;
//                    TreeNode<K, V> pl = p.left;
//                    TreeNode<K, V> pr = p.right;
//                    if (pl != null && pr != null) {
//                        TreeNode<K, V> s = pr, sl;
//                        while ((sl = s.left) != null) // find successor
//                            s = sl;
//                        boolean c = s.red;
//                        s.red = p.red;
//                        p.red = c; // swap colors
//                        TreeNode<K, V> sr = s.right;
//                        TreeNode<K, V> pp = p.parent;
//                        if (s == pr) { // p was s's direct parent
//                            p.parent = s;
//                            s.right = p;
//                        } else {
//                            TreeNode<K, V> sp = s.parent;
//                            if ((p.parent = sp) != null) {
//                                if (s == sp.left)
//                                    sp.left = p;
//                                else
//                                    sp.right = p;
//                            }
//                            if ((s.right = pr) != null)
//                                pr.parent = s;
//                        }
//                        p.left = null;
//                        if ((p.right = sr) != null)
//                            sr.parent = p;
//                        if ((s.left = pl) != null)
//                            pl.parent = s;
//                        if ((s.parent = pp) == null)
//                            r = s;
//                        else if (p == pp.left)
//                            pp.left = s;
//                        else
//                            pp.right = s;
//                        if (sr != null)
//                            replacement = sr;
//                        else
//                            replacement = p;
//                    } else if (pl != null)
//                        replacement = pl;
//                    else if (pr != null)
//                        replacement = pr;
//                    else
//                        replacement = p;
//                    if (replacement != p) {
//                        TreeNode<K, V> pp = replacement.parent = p.parent;
//                        if (pp == null)
//                            r = replacement;
//                        else if (p == pp.left)
//                            pp.left = replacement;
//                        else
//                            pp.right = replacement;
//                        p.left = p.right = p.parent = null;
//                    }
//
//                    root = (p.red) ? r : balanceDeletion(r, replacement);
//
//                    if (p == replacement) {  // detach pointers
//                        TreeNode<K, V> pp;
//                        if ((pp = p.parent) != null) {
//                            if (p == pp.left)
//                                pp.left = null;
//                            else if (p == pp.right)
//                                pp.right = null;
//                            p.parent = null;
//                        }
//                    }
//                } finally {
//                    unlockRoot();
//                }
//                assert checkInvariants(root);
//                return false;
//            }
//
//        /* ------------------------------------------------------------ */
//            // Red-black tree methods, all adapted from CLR
//
//            static <K, V> TreeNode<K, V> rotateLeft(TreeNode<K, V> root, TreeNode<K, V> p) {
//                TreeNode<K, V> r, pp, rl;
//                if (p != null && (r = p.right) != null) {
//                    if ((rl = p.right = r.left) != null)
//                        rl.parent = p;
//                    if ((pp = r.parent = p.parent) == null)
//                        (root = r).red = false;
//                    else if (pp.left == p)
//                        pp.left = r;
//                    else
//                        pp.right = r;
//                    r.left = p;
//                    p.parent = r;
//                }
//                return root;
//            }
//
//            static <K, V> TreeNode<K, V> rotateRight(TreeNode<K, V> root, TreeNode<K, V> p) {
//                TreeNode<K, V> l, pp, lr;
//                if (p != null && (l = p.left) != null) {
//                    if ((lr = p.left = l.right) != null)
//                        lr.parent = p;
//                    if ((pp = l.parent = p.parent) == null)
//                        (root = l).red = false;
//                    else if (pp.right == p)
//                        pp.right = l;
//                    else
//                        pp.left = l;
//                    l.right = p;
//                    p.parent = l;
//                }
//                return root;
//            }
//
//            static <K, V> TreeNode<K, V> balanceInsertion(TreeNode<K, V> root, TreeNode<K, V> x) {
//                x.red = true;
//                for (TreeNode<K, V> xp, xpp, xppl, xppr; ; ) {
//                    if ((xp = x.parent) == null) {
//                        x.red = false;
//                        return x;
//                    } else if (!xp.red || (xpp = xp.parent) == null)
//                        return root;
//                    if (xp == (xppl = xpp.left)) {
//                        if ((xppr = xpp.right) != null && xppr.red) {
//                            xppr.red = false;
//                            xp.red = false;
//                            xpp.red = true;
//                            x = xpp;
//                        } else {
//                            if (x == xp.right) {
//                                root = rotateLeft(root, x = xp);
//                                xpp = (xp = x.parent) == null ? null : xp.parent;
//                            }
//                            if (xp != null) {
//                                xp.red = false;
//                                if (xpp != null) {
//                                    xpp.red = true;
//                                    root = rotateRight(root, xpp);
//                                }
//                            }
//                        }
//                    } else {
//                        if (xppl != null && xppl.red) {
//                            xppl.red = false;
//                            xp.red = false;
//                            xpp.red = true;
//                            x = xpp;
//                        } else {
//                            if (x == xp.left) {
//                                root = rotateRight(root, x = xp);
//                                xpp = (xp = x.parent) == null ? null : xp.parent;
//                            }
//                            if (xp != null) {
//                                xp.red = false;
//                                if (xpp != null) {
//                                    xpp.red = true;
//                                    root = rotateLeft(root, xpp);
//                                }
//                            }
//                        }
//                    }
//                }
//            }
//
//            static <K, V> TreeNode<K, V> balanceDeletion(TreeNode<K, V> root, TreeNode<K, V> x) {
//                for (TreeNode<K, V> xp, xpl, xpr; ; ) {
//                    if (x == null || x == root)
//                        return root;
//                    else if ((xp = x.parent) == null) {
//                        x.red = false;
//                        return x;
//                    } else if (x.red) {
//                        x.red = false;
//                        return root;
//                    } else if ((xpl = xp.left) == x) {
//                        if ((xpr = xp.right) != null && xpr.red) {
//                            xpr.red = false;
//                            xp.red = true;
//                            root = rotateLeft(root, xp);
//                            xpr = (xp = x.parent) == null ? null : xp.right;
//                        }
//                        if (xpr == null)
//                            x = xp;
//                        else {
//                            TreeNode<K, V> sl = xpr.left, sr = xpr.right;
//                            if ((sr == null || !sr.red) && (sl == null || !sl.red)) {
//                                xpr.red = true;
//                                x = xp;
//                            } else {
//                                if (sr == null || !sr.red) {
//                                    if (sl != null)
//                                        sl.red = false;
//                                    xpr.red = true;
//                                    root = rotateRight(root, xpr);
//                                    xpr = (xp = x.parent) == null ? null : xp.right;
//                                }
//                                if (xpr != null) {
//                                    xpr.red = (xp == null) ? false : xp.red;
//                                    if ((sr = xpr.right) != null)
//                                        sr.red = false;
//                                }
//                                if (xp != null) {
//                                    xp.red = false;
//                                    root = rotateLeft(root, xp);
//                                }
//                                x = root;
//                            }
//                        }
//                    } else { // symmetric
//                        if (xpl != null && xpl.red) {
//                            xpl.red = false;
//                            xp.red = true;
//                            root = rotateRight(root, xp);
//                            xpl = (xp = x.parent) == null ? null : xp.left;
//                        }
//                        if (xpl == null)
//                            x = xp;
//                        else {
//                            TreeNode<K, V> sl = xpl.left, sr = xpl.right;
//                            if ((sl == null || !sl.red) && (sr == null || !sr.red)) {
//                                xpl.red = true;
//                                x = xp;
//                            } else {
//                                if (sl == null || !sl.red) {
//                                    if (sr != null)
//                                        sr.red = false;
//                                    xpl.red = true;
//                                    root = rotateLeft(root, xpl);
//                                    xpl = (xp = x.parent) == null ? null : xp.left;
//                                }
//                                if (xpl != null) {
//                                    xpl.red = (xp == null) ? false : xp.red;
//                                    if ((sl = xpl.left) != null)
//                                        sl.red = false;
//                                }
//                                if (xp != null) {
//                                    xp.red = false;
//                                    root = rotateRight(root, xp);
//                                }
//                                x = root;
//                            }
//                        }
//                    }
//                }
//            }
//
//            /**
//             * Recursive invariant check
//             */
//            static <K, V> boolean checkInvariants(TreeNode<K, V> t) {
//                TreeNode<K, V> tp = t.parent, tl = t.left, tr = t.right, tb = t.prev, tn = (TreeNode<K, V>) t.next;
//                if (tb != null && tb.next != t)
//                    return false;
//                if (tn != null && tn.prev != t)
//                    return false;
//                if (tp != null && t != tp.left && t != tp.right)
//                    return false;
//                if (tl != null && (tl.parent != t || tl.hash > t.hash))
//                    return false;
//                if (tr != null && (tr.parent != t || tr.hash < t.hash))
//                    return false;
//                if (t.red && tl != null && tl.red && tr != null && tr.red)
//                    return false;
//                if (tl != null && !checkInvariants(tl))
//                    return false;
//                if (tr != null && !checkInvariants(tr))
//                    return false;
//                return true;
//            }
//
//            private static final sun.misc.Unsafe U;
//            private static final long LOCKSTATE;
//
//            static {
//                try {
//                    U = sun.misc.Unsafe.getUnsafe();
//                    Class<?> k = TreeBin.class;
//                    LOCKSTATE = U.objectFieldOffset(k.getDeclaredField("lockState"));
//                } catch (Exception e) {
//                    throw new Error(e);
//                }
//            }
//        }
//
//    /* ----------------Table Traversal -------------- */
//
//        /**
//         * Records the table, its length, and current traversal index for a
//         * traverser that must process a region of a forwarded table before
//         * proceeding with current table.
//         */
//        static final class TableStack<K, V> {
//            int length;
//            int index;
//            Node<K, V>[] tab;
//            TableStack<K, V> next;
//        }
//
//        /**
//         * Encapsulates traversal for methods such as containsValue; also
//         * serves as a base class for other iterators and spliterators.
//         * <p>
//         * Method advance visits once each still-valid node that was
//         * reachable upon iterator construction. It might miss some that
//         * were added to a bin after the bin was visited, which is OK wrt
//         * consistency guarantees. Maintaining this property in the face
//         * of possible ongoing resizes requires a fair amount of
//         * bookkeeping state that is difficult to optimize away amidst
//         * volatile accesses.  Even so, traversal maintains reasonable
//         * throughput.
//         * <p>
//         * Normally, iteration proceeds bin-by-bin traversing lists.
//         * However, if the table has been resized, then all future steps
//         * must traverse both the bin at the current index as well as at
//         * (index + baseSize); and so on for further resizings. To
//         * paranoically cope with potential sharing by users of iterators
//         * across threads, iteration terminates if a bounds checks fails
//         * for a table read.
//         */
//        static class Traverser<K, V> {
//            Node<K, V>[] tab;        // current table; updated if resized
//            Node<K, V> next;         // the next entry to use
//            TableStack<K, V> stack, spare; // to save/restore on ForwardingNodes
//            int index;              // index of bin to use next
//            int baseIndex;          // current index of initial table
//            int baseLimit;          // index bound for initial table
//            final int baseSize;     // initial table size
//
//            Traverser(Node<K, V>[] tab, int size, int index, int limit) {
//                this.tab = tab;
//                this.baseSize = size;
//                this.baseIndex = this.index = index;
//                this.baseLimit = limit;
//                this.next = null;
//            }
//
//            /**
//             * Advances if possible, returning next valid node, or null if none.
//             */
//            final Node<K, V> advance() {
//                Node<K, V> e;
//                if ((e = next) != null)
//                    e = e.next;
//                for (; ; ) {
//                    Node<K, V>[] t;
//                    int i, n;  // must use locals in checks
//                    if (e != null)
//                        return next = e;
//                    if (baseIndex >= baseLimit || (t = tab) == null || (n = t.length) <= (i = index) || i < 0)
//                        return next = null;
//                    if ((e = tabAt(t, i)) != null && e.hash < 0) {
//                        if (e instanceof ForwardingNode) {
//                            tab = ((ForwardingNode<K, V>) e).nextTable;
//                            e = null;
//                            pushState(t, i, n);
//                            continue;
//                        } else if (e instanceof TreeBin)
//                            e = ((TreeBin<K, V>) e).first;
//                        else
//                            e = null;
//                    }
//                    if (stack != null)
//                        recoverState(n);
//                    else if ((index = i + baseSize) >= n)
//                        index = ++baseIndex; // visit upper slots if present
//                }
//            }
//
//            /**
//             * Saves traversal state upon encountering a forwarding node.
//             */
//            private void pushState(Node<K, V>[] t, int i, int n) {
//                TableStack<K, V> s = spare;  // reuse if possible
//                if (s != null)
//                    spare = s.next;
//                else
//                    s = new TableStack<K, V>();
//                s.tab = t;
//                s.length = n;
//                s.index = i;
//                s.next = stack;
//                stack = s;
//            }
//
//            /**
//             * Possibly pops traversal state.
//             *
//             * @param n length of current table
//             */
//            private void recoverState(int n) {
//                TableStack<K, V> s;
//                int len;
//                while ((s = stack) != null && (index += (len = s.length)) >= n) {
//                    n = len;
//                    index = s.index;
//                    tab = s.tab;
//                    s.tab = null;
//                    TableStack<K, V> next = s.next;
//                    s.next = spare; // save for reuse
//                    stack = next;
//                    spare = s;
//                }
//                if (s == null && (index += baseSize) >= n)
//                    index = ++baseIndex;
//            }
//        }
//
//        /**
//         * Base of key, value, and entry Iterators. Adds fields to
//         * Traverser to support iterator.remove.
//         */
//        static class BaseIterator<K, V> extends Traverser<K, V> {
//            final ConcurrentHashMap<K, V> map;
//            Node<K, V> lastReturned;
//
//            BaseIterator(Node<K, V>[] tab, int size, int index, int limit, ConcurrentHashMap<K, V> map) {
//                super(tab, size, index, limit);
//                this.map = map;
//                advance();
//            }
//
//            public final boolean hasNext() {
//                return next != null;
//            }
//
//            public final boolean hasMoreElements() {
//                return next != null;
//            }
//
//            public final void remove() {
//                Node<K, V> p;
//                if ((p = lastReturned) == null)
//                    throw new IllegalStateException();
//                lastReturned = null;
//                map.replaceNode(p.key, null, null);
//            }
//        }
//
//        static final class KeyIterator<K, V> extends BaseIterator<K, V> implements Iterator<K>, Enumeration<K> {
//            KeyIterator(Node<K, V>[] tab, int index, int size, int limit, ConcurrentHashMap<K, V> map) {
//                super(tab, index, size, limit, map);
//            }
//
//            public final K next() {
//                Node<K, V> p;
//                if ((p = next) == null)
//                    throw new NoSuchElementException();
//                K k = p.key;
//                lastReturned = p;
//                advance();
//                return k;
//            }
//
//            public final K nextElement() {
//                return next();
//            }
//        }
//
//        static final class ValueIterator<K, V> extends BaseIterator<K, V> implements Iterator<V>, Enumeration<V> {
//            ValueIterator(Node<K, V>[] tab, int index, int size, int limit, ConcurrentHashMap<K, V> map) {
//                super(tab, index, size, limit, map);
//            }
//
//            public final V next() {
//                Node<K, V> p;
//                if ((p = next) == null)
//                    throw new NoSuchElementException();
//                V v = p.val;
//                lastReturned = p;
//                advance();
//                return v;
//            }
//
//            public final V nextElement() {
//                return next();
//            }
//        }
//
//        static final class EntryIterator<K, V> extends BaseIterator<K, V> implements Iterator<Map.Entry<K, V>> {
//            EntryIterator(Node<K, V>[] tab, int index, int size, int limit, ConcurrentHashMap<K, V> map) {
//                super(tab, index, size, limit, map);
//            }
//
//            public final Map.Entry<K, V> next() {
//                Node<K, V> p;
//                if ((p = next) == null)
//                    throw new NoSuchElementException();
//                K k = p.key;
//                V v = p.val;
//                lastReturned = p;
//                advance();
//                return new MapEntry<K, V>(k, v, map);
//            }
//        }
//
//        /**
//         * Exported Entry for EntryIterator
//         */
//        static final class MapEntry<K, V> implements Map.Entry<K, V> {
//            final K key; // non-null
//            V val;       // non-null
//            final ConcurrentHashMap<K, V> map;
//
//            MapEntry(K key, V val, ConcurrentHashMap<K, V> map) {
//                this.key = key;
//                this.val = val;
//                this.map = map;
//            }
//
//            public K getKey() {
//                return key;
//            }
//
//            public V getValue() {
//                return val;
//            }
//
//            public int hashCode() {
//                return key.hashCode() ^ val.hashCode();
//            }
//
//            public String toString() {
//                return key + "=" + val;
//            }
//
//            public boolean equals(Object o) {
//                Object k, v;
//                Map.Entry<?, ?> e;
//                return ((o instanceof Map.Entry) && (k = (e = (Map.Entry<?, ?>) o).getKey()) != null && (v = e.getValue()) != null && (k == key || k.equals(key)) && (v == val || v.equals(val)));
//            }
//
//            /**
//             * Sets our entry's value and writes through to the map. The
//             * value to return is somewhat arbitrary here. Since we do not
//             * necessarily track asynchronous changes, the most recent
//             * "previous" value could be different from what we return (or
//             * could even have been removed, in which case the put will
//             * re-establish). We do not and cannot guarantee more.
//             */
//            public V setValue(V value) {
//                if (value == null)
//                    throw new NullPointerException();
//                V v = val;
//                val = value;
//                map.put(key, value);
//                return v;
//            }
//        }
//
//        static final class KeySpliterator<K, V> extends Traverser<K, V> implements Spliterator<K> {
//            long est;               // size estimate
//
//            KeySpliterator(Node<K, V>[] tab, int size, int index, int limit, long est) {
//                super(tab, size, index, limit);
//                this.est = est;
//            }
//
//            public Spliterator<K> trySplit() {
//                int i, f, h;
//                return (h = ((i = baseIndex) + (f = baseLimit)) >>> 1) <= i ? null : new KeySpliterator<K, V>(tab, baseSize, baseLimit = h, f, est >>>= 1);
//            }
//
//            public void forEachRemaining(Consumer<? super K> action) {
//                if (action == null)
//                    throw new NullPointerException();
//                for (Node<K, V> p; (p = advance()) != null; )
//                    action.accept(p.key);
//            }
//
//            public boolean tryAdvance(Consumer<? super K> action) {
//                if (action == null)
//                    throw new NullPointerException();
//                Node<K, V> p;
//                if ((p = advance()) == null)
//                    return false;
//                action.accept(p.key);
//                return true;
//            }
//
//            public long estimateSize() {
//                return est;
//            }
//
//            public int characteristics() {
//                return Spliterator.DISTINCT | Spliterator.CONCURRENT | Spliterator.NONNULL;
//            }
//        }
//
//        static final class ValueSpliterator<K, V> extends Traverser<K, V> implements Spliterator<V> {
//            long est;               // size estimate
//
//            ValueSpliterator(Node<K, V>[] tab, int size, int index, int limit, long est) {
//                super(tab, size, index, limit);
//                this.est = est;
//            }
//
//            public Spliterator<V> trySplit() {
//                int i, f, h;
//                return (h = ((i = baseIndex) + (f = baseLimit)) >>> 1) <= i ? null : new ValueSpliterator<K, V>(tab, baseSize, baseLimit = h, f, est >>>= 1);
//            }
//
//            public void forEachRemaining(Consumer<? super V> action) {
//                if (action == null)
//                    throw new NullPointerException();
//                for (Node<K, V> p; (p = advance()) != null; )
//                    action.accept(p.val);
//            }
//
//            public boolean tryAdvance(Consumer<? super V> action) {
//                if (action == null)
//                    throw new NullPointerException();
//                Node<K, V> p;
//                if ((p = advance()) == null)
//                    return false;
//                action.accept(p.val);
//                return true;
//            }
//
//            public long estimateSize() {
//                return est;
//            }
//
//            public int characteristics() {
//                return Spliterator.CONCURRENT | Spliterator.NONNULL;
//            }
//        }
//
//        static final class EntrySpliterator<K, V> extends Traverser<K, V> implements Spliterator<Map.Entry<K, V>> {
//            final ConcurrentHashMap<K, V> map; // To export MapEntry
//            long est;               // size estimate
//
//            EntrySpliterator(Node<K, V>[] tab, int size, int index, int limit, long est, ConcurrentHashMap<K, V> map) {
//                super(tab, size, index, limit);
//                this.map = map;
//                this.est = est;
//            }
//
//            public Spliterator<Map.Entry<K, V>> trySplit() {
//                int i, f, h;
//                return (h = ((i = baseIndex) + (f = baseLimit)) >>> 1) <= i ? null : new EntrySpliterator<K, V>(tab, baseSize, baseLimit = h, f, est >>>= 1, map);
//            }
//
//            public void forEachRemaining(Consumer<? super Map.Entry<K, V>> action) {
//                if (action == null)
//                    throw new NullPointerException();
//                for (Node<K, V> p; (p = advance()) != null; )
//                    action.accept(new MapEntry<K, V>(p.key, p.val, map));
//            }
//
//            public boolean tryAdvance(Consumer<? super Map.Entry<K, V>> action) {
//                if (action == null)
//                    throw new NullPointerException();
//                Node<K, V> p;
//                if ((p = advance()) == null)
//                    return false;
//                action.accept(new MapEntry<K, V>(p.key, p.val, map));
//                return true;
//            }
//
//            public long estimateSize() {
//                return est;
//            }
//
//            public int characteristics() {
//                return Spliterator.DISTINCT | Spliterator.CONCURRENT | Spliterator.NONNULL;
//            }
//        }
//
//        // Parallel bulk operations
//
//        /**
//         * Computes initial batch value for bulk tasks. The returned value
//         * is approximately exp2 of the number of times (minus one) to
//         * split task by two before executing leaf action. This value is
//         * faster to compute and more convenient to use as a guide to
//         * splitting than is the depth, since it is used while dividing by
//         * two anyway.
//         */
//        final int batchFor(long b) {
//            long n;
//            if (b == Long.MAX_VALUE || (n = sumCount()) <= 1L || n < b)
//                return 0;
//            int sp = ForkJoinPool.getCommonPoolParallelism() << 2; // slack of 4
//            return (b <= 0L || (n /= b) >= sp) ? sp : (int) n;
//        }
//
//        /**
//         * Performs the given action for each (key, value).
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param action               the action
//         * @since 1.8
//         */
//        public void forEach(long parallelismThreshold, BiConsumer<? super K, ? super V> action) {
//            if (action == null)
//                throw new NullPointerException();
//            new ForEachMappingTask<K, V>(null, batchFor(parallelismThreshold), 0, 0, table, action).invoke();
//        }
//
//        /**
//         * Performs the given action for each non-null transformation
//         * of each (key, value).
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param transformer          a function returning the transformation
//         *                             for an element, or null if there is no transformation (in
//         *                             which case the action is not applied)
//         * @param action               the action
//         * @param <U>                  the return type of the transformer
//         * @since 1.8
//         */
//        public <U> void forEach(long parallelismThreshold, BiFunction<? super K, ? super V, ? extends U> transformer, Consumer<? super U> action) {
//            if (transformer == null || action == null)
//                throw new NullPointerException();
//            new ForEachTransformedMappingTask<K, V, U>(null, batchFor(parallelismThreshold), 0, 0, table, transformer, action).invoke();
//        }
//
//        /**
//         * Returns a non-null result from applying the given search
//         * function on each (key, value), or null if none.  Upon
//         * success, further element processing is suppressed and the
//         * results of any other parallel invocations of the search
//         * function are ignored.
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param searchFunction       a function returning a non-null
//         *                             result on success, else null
//         * @param <U>                  the return type of the search function
//         * @return a non-null result from applying the given search
//         * function on each (key, value), or null if none
//         * @since 1.8
//         */
//        public <U> U search(long parallelismThreshold, BiFunction<? super K, ? super V, ? extends U> searchFunction) {
//            if (searchFunction == null)
//                throw new NullPointerException();
//            return new SearchMappingsTask<K, V, U>(null, batchFor(parallelismThreshold), 0, 0, table, searchFunction, new AtomicReference<U>()).invoke();
//        }
//
//        /**
//         * Returns the result of accumulating the given transformation
//         * of all (key, value) pairs using the given reducer to
//         * combine values, or null if none.
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param transformer          a function returning the transformation
//         *                             for an element, or null if there is no transformation (in
//         *                             which case it is not combined)
//         * @param reducer              a commutative associative combining function
//         * @param <U>                  the return type of the transformer
//         * @return the result of accumulating the given transformation
//         * of all (key, value) pairs
//         * @since 1.8
//         */
//        public <U> U reduce(long parallelismThreshold, BiFunction<? super K, ? super V, ? extends U> transformer, BiFunction<? super U, ? super U, ? extends U> reducer) {
//            if (transformer == null || reducer == null)
//                throw new NullPointerException();
//            return new MapReduceMappingsTask<K, V, U>(null, batchFor(parallelismThreshold), 0, 0, table, null, transformer, reducer).invoke();
//        }
//
//        /**
//         * Returns the result of accumulating the given transformation
//         * of all (key, value) pairs using the given reducer to
//         * combine values, and the given basis as an identity value.
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param transformer          a function returning the transformation
//         *                             for an element
//         * @param basis                the identity (initial default value) for the reduction
//         * @param reducer              a commutative associative combining function
//         * @return the result of accumulating the given transformation
//         * of all (key, value) pairs
//         * @since 1.8
//         */
//        public double reduceToDouble(long parallelismThreshold, ToDoubleBiFunction<? super K, ? super V> transformer, double basis, DoubleBinaryOperator reducer) {
//            if (transformer == null || reducer == null)
//                throw new NullPointerException();
//            return new MapReduceMappingsToDoubleTask<K, V>(null, batchFor(parallelismThreshold), 0, 0, table, null, transformer, basis, reducer).invoke();
//        }
//
//        /**
//         * Returns the result of accumulating the given transformation
//         * of all (key, value) pairs using the given reducer to
//         * combine values, and the given basis as an identity value.
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param transformer          a function returning the transformation
//         *                             for an element
//         * @param basis                the identity (initial default value) for the reduction
//         * @param reducer              a commutative associative combining function
//         * @return the result of accumulating the given transformation
//         * of all (key, value) pairs
//         * @since 1.8
//         */
//        public long reduceToLong(long parallelismThreshold, ToLongBiFunction<? super K, ? super V> transformer, long basis, LongBinaryOperator reducer) {
//            if (transformer == null || reducer == null)
//                throw new NullPointerException();
//            return new MapReduceMappingsToLongTask<K, V>(null, batchFor(parallelismThreshold), 0, 0, table, null, transformer, basis, reducer).invoke();
//        }
//
//        /**
//         * Returns the result of accumulating the given transformation
//         * of all (key, value) pairs using the given reducer to
//         * combine values, and the given basis as an identity value.
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param transformer          a function returning the transformation
//         *                             for an element
//         * @param basis                the identity (initial default value) for the reduction
//         * @param reducer              a commutative associative combining function
//         * @return the result of accumulating the given transformation
//         * of all (key, value) pairs
//         * @since 1.8
//         */
//        public int reduceToInt(long parallelismThreshold, ToIntBiFunction<? super K, ? super V> transformer, int basis, IntBinaryOperator reducer) {
//            if (transformer == null || reducer == null)
//                throw new NullPointerException();
//            return new MapReduceMappingsToIntTask<K, V>(null, batchFor(parallelismThreshold), 0, 0, table, null, transformer, basis, reducer).invoke();
//        }
//
//        /**
//         * Performs the given action for each key.
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param action               the action
//         * @since 1.8
//         */
//        public void forEachKey(long parallelismThreshold, Consumer<? super K> action) {
//            if (action == null)
//                throw new NullPointerException();
//            new ForEachKeyTask<K, V>(null, batchFor(parallelismThreshold), 0, 0, table, action).invoke();
//        }
//
//        /**
//         * Performs the given action for each non-null transformation
//         * of each key.
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param transformer          a function returning the transformation
//         *                             for an element, or null if there is no transformation (in
//         *                             which case the action is not applied)
//         * @param action               the action
//         * @param <U>                  the return type of the transformer
//         * @since 1.8
//         */
//        public <U> void forEachKey(long parallelismThreshold, Function<? super K, ? extends U> transformer, Consumer<? super U> action) {
//            if (transformer == null || action == null)
//                throw new NullPointerException();
//            new ForEachTransformedKeyTask<K, V, U>(null, batchFor(parallelismThreshold), 0, 0, table, transformer, action).invoke();
//        }
//
//        /**
//         * Returns a non-null result from applying the given search
//         * function on each key, or null if none. Upon success,
//         * further element processing is suppressed and the results of
//         * any other parallel invocations of the search function are
//         * ignored.
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param searchFunction       a function returning a non-null
//         *                             result on success, else null
//         * @param <U>                  the return type of the search function
//         * @return a non-null result from applying the given search
//         * function on each key, or null if none
//         * @since 1.8
//         */
//        public <U> U searchKeys(long parallelismThreshold, Function<? super K, ? extends U> searchFunction) {
//            if (searchFunction == null)
//                throw new NullPointerException();
//            return new SearchKeysTask<K, V, U>(null, batchFor(parallelismThreshold), 0, 0, table, searchFunction, new AtomicReference<U>()).invoke();
//        }
//
//        /**
//         * Returns the result of accumulating all keys using the given
//         * reducer to combine values, or null if none.
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param reducer              a commutative associative combining function
//         * @return the result of accumulating all keys using the given
//         * reducer to combine values, or null if none
//         * @since 1.8
//         */
//        public K reduceKeys(long parallelismThreshold, BiFunction<? super K, ? super K, ? extends K> reducer) {
//            if (reducer == null)
//                throw new NullPointerException();
//            return new ReduceKeysTask<K, V>(null, batchFor(parallelismThreshold), 0, 0, table, null, reducer).invoke();
//        }
//
//        /**
//         * Returns the result of accumulating the given transformation
//         * of all keys using the given reducer to combine values, or
//         * null if none.
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param transformer          a function returning the transformation
//         *                             for an element, or null if there is no transformation (in
//         *                             which case it is not combined)
//         * @param reducer              a commutative associative combining function
//         * @param <U>                  the return type of the transformer
//         * @return the result of accumulating the given transformation
//         * of all keys
//         * @since 1.8
//         */
//        public <U> U reduceKeys(long parallelismThreshold, Function<? super K, ? extends U> transformer, BiFunction<? super U, ? super U, ? extends U> reducer) {
//            if (transformer == null || reducer == null)
//                throw new NullPointerException();
//            return new MapReduceKeysTask<K, V, U>(null, batchFor(parallelismThreshold), 0, 0, table, null, transformer, reducer).invoke();
//        }
//
//        /**
//         * Returns the result of accumulating the given transformation
//         * of all keys using the given reducer to combine values, and
//         * the given basis as an identity value.
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param transformer          a function returning the transformation
//         *                             for an element
//         * @param basis                the identity (initial default value) for the reduction
//         * @param reducer              a commutative associative combining function
//         * @return the result of accumulating the given transformation
//         * of all keys
//         * @since 1.8
//         */
//        public double reduceKeysToDouble(long parallelismThreshold, ToDoubleFunction<? super K> transformer, double basis, DoubleBinaryOperator reducer) {
//            if (transformer == null || reducer == null)
//                throw new NullPointerException();
//            return new MapReduceKeysToDoubleTask<K, V>(null, batchFor(parallelismThreshold), 0, 0, table, null, transformer, basis, reducer).invoke();
//        }
//
//        /**
//         * Returns the result of accumulating the given transformation
//         * of all keys using the given reducer to combine values, and
//         * the given basis as an identity value.
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param transformer          a function returning the transformation
//         *                             for an element
//         * @param basis                the identity (initial default value) for the reduction
//         * @param reducer              a commutative associative combining function
//         * @return the result of accumulating the given transformation
//         * of all keys
//         * @since 1.8
//         */
//        public long reduceKeysToLong(long parallelismThreshold, ToLongFunction<? super K> transformer, long basis, LongBinaryOperator reducer) {
//            if (transformer == null || reducer == null)
//                throw new NullPointerException();
//            return new MapReduceKeysToLongTask<K, V>(null, batchFor(parallelismThreshold), 0, 0, table, null, transformer, basis, reducer).invoke();
//        }
//
//        /**
//         * Returns the result of accumulating the given transformation
//         * of all keys using the given reducer to combine values, and
//         * the given basis as an identity value.
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param transformer          a function returning the transformation
//         *                             for an element
//         * @param basis                the identity (initial default value) for the reduction
//         * @param reducer              a commutative associative combining function
//         * @return the result of accumulating the given transformation
//         * of all keys
//         * @since 1.8
//         */
//        public int reduceKeysToInt(long parallelismThreshold, ToIntFunction<? super K> transformer, int basis, IntBinaryOperator reducer) {
//            if (transformer == null || reducer == null)
//                throw new NullPointerException();
//            return new MapReduceKeysToIntTask<K, V>(null, batchFor(parallelismThreshold), 0, 0, table, null, transformer, basis, reducer).invoke();
//        }
//
//        /**
//         * Performs the given action for each value.
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param action               the action
//         * @since 1.8
//         */
//        public void forEachValue(long parallelismThreshold, Consumer<? super V> action) {
//            if (action == null)
//                throw new NullPointerException();
//            new ForEachValueTask<K, V>(null, batchFor(parallelismThreshold), 0, 0, table, action).invoke();
//        }
//
//        /**
//         * Performs the given action for each non-null transformation
//         * of each value.
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param transformer          a function returning the transformation
//         *                             for an element, or null if there is no transformation (in
//         *                             which case the action is not applied)
//         * @param action               the action
//         * @param <U>                  the return type of the transformer
//         * @since 1.8
//         */
//        public <U> void forEachValue(long parallelismThreshold, Function<? super V, ? extends U> transformer, Consumer<? super U> action) {
//            if (transformer == null || action == null)
//                throw new NullPointerException();
//            new ForEachTransformedValueTask<K, V, U>(null, batchFor(parallelismThreshold), 0, 0, table, transformer, action).invoke();
//        }
//
//        /**
//         * Returns a non-null result from applying the given search
//         * function on each value, or null if none.  Upon success,
//         * further element processing is suppressed and the results of
//         * any other parallel invocations of the search function are
//         * ignored.
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param searchFunction       a function returning a non-null
//         *                             result on success, else null
//         * @param <U>                  the return type of the search function
//         * @return a non-null result from applying the given search
//         * function on each value, or null if none
//         * @since 1.8
//         */
//        public <U> U searchValues(long parallelismThreshold, Function<? super V, ? extends U> searchFunction) {
//            if (searchFunction == null)
//                throw new NullPointerException();
//            return new SearchValuesTask<K, V, U>(null, batchFor(parallelismThreshold), 0, 0, table, searchFunction, new AtomicReference<U>()).invoke();
//        }
//
//        /**
//         * Returns the result of accumulating all values using the
//         * given reducer to combine values, or null if none.
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param reducer              a commutative associative combining function
//         * @return the result of accumulating all values
//         * @since 1.8
//         */
//        public V reduceValues(long parallelismThreshold, BiFunction<? super V, ? super V, ? extends V> reducer) {
//            if (reducer == null)
//                throw new NullPointerException();
//            return new ReduceValuesTask<K, V>(null, batchFor(parallelismThreshold), 0, 0, table, null, reducer).invoke();
//        }
//
//        /**
//         * Returns the result of accumulating the given transformation
//         * of all values using the given reducer to combine values, or
//         * null if none.
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param transformer          a function returning the transformation
//         *                             for an element, or null if there is no transformation (in
//         *                             which case it is not combined)
//         * @param reducer              a commutative associative combining function
//         * @param <U>                  the return type of the transformer
//         * @return the result of accumulating the given transformation
//         * of all values
//         * @since 1.8
//         */
//        public <U> U reduceValues(long parallelismThreshold, Function<? super V, ? extends U> transformer, BiFunction<? super U, ? super U, ? extends U> reducer) {
//            if (transformer == null || reducer == null)
//                throw new NullPointerException();
//            return new MapReduceValuesTask<K, V, U>(null, batchFor(parallelismThreshold), 0, 0, table, null, transformer, reducer).invoke();
//        }
//
//        /**
//         * Returns the result of accumulating the given transformation
//         * of all values using the given reducer to combine values,
//         * and the given basis as an identity value.
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param transformer          a function returning the transformation
//         *                             for an element
//         * @param basis                the identity (initial default value) for the reduction
//         * @param reducer              a commutative associative combining function
//         * @return the result of accumulating the given transformation
//         * of all values
//         * @since 1.8
//         */
//        public double reduceValuesToDouble(long parallelismThreshold, ToDoubleFunction<? super V> transformer, double basis, DoubleBinaryOperator reducer) {
//            if (transformer == null || reducer == null)
//                throw new NullPointerException();
//            return new MapReduceValuesToDoubleTask<K, V>(null, batchFor(parallelismThreshold), 0, 0, table, null, transformer, basis, reducer).invoke();
//        }
//
//        /**
//         * Returns the result of accumulating the given transformation
//         * of all values using the given reducer to combine values,
//         * and the given basis as an identity value.
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param transformer          a function returning the transformation
//         *                             for an element
//         * @param basis                the identity (initial default value) for the reduction
//         * @param reducer              a commutative associative combining function
//         * @return the result of accumulating the given transformation
//         * of all values
//         * @since 1.8
//         */
//        public long reduceValuesToLong(long parallelismThreshold, ToLongFunction<? super V> transformer, long basis, LongBinaryOperator reducer) {
//            if (transformer == null || reducer == null)
//                throw new NullPointerException();
//            return new MapReduceValuesToLongTask<K, V>(null, batchFor(parallelismThreshold), 0, 0, table, null, transformer, basis, reducer).invoke();
//        }
//
//        /**
//         * Returns the result of accumulating the given transformation
//         * of all values using the given reducer to combine values,
//         * and the given basis as an identity value.
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param transformer          a function returning the transformation
//         *                             for an element
//         * @param basis                the identity (initial default value) for the reduction
//         * @param reducer              a commutative associative combining function
//         * @return the result of accumulating the given transformation
//         * of all values
//         * @since 1.8
//         */
//        public int reduceValuesToInt(long parallelismThreshold, ToIntFunction<? super V> transformer, int basis, IntBinaryOperator reducer) {
//            if (transformer == null || reducer == null)
//                throw new NullPointerException();
//            return new MapReduceValuesToIntTask<K, V>(null, batchFor(parallelismThreshold), 0, 0, table, null, transformer, basis, reducer).invoke();
//        }
//
//        /**
//         * Performs the given action for each entry.
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param action               the action
//         * @since 1.8
//         */
//        public void forEachEntry(long parallelismThreshold, Consumer<? super Map.Entry<K, V>> action) {
//            if (action == null)
//                throw new NullPointerException();
//            new ForEachEntryTask<K, V>(null, batchFor(parallelismThreshold), 0, 0, table, action).invoke();
//        }
//
//        /**
//         * Performs the given action for each non-null transformation
//         * of each entry.
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param transformer          a function returning the transformation
//         *                             for an element, or null if there is no transformation (in
//         *                             which case the action is not applied)
//         * @param action               the action
//         * @param <U>                  the return type of the transformer
//         * @since 1.8
//         */
//        public <U> void forEachEntry(long parallelismThreshold, Function<Map.Entry<K, V>, ? extends U> transformer, Consumer<? super U> action) {
//            if (transformer == null || action == null)
//                throw new NullPointerException();
//            new ForEachTransformedEntryTask<K, V, U>(null, batchFor(parallelismThreshold), 0, 0, table, transformer, action).invoke();
//        }
//
//        /**
//         * Returns a non-null result from applying the given search
//         * function on each entry, or null if none.  Upon success,
//         * further element processing is suppressed and the results of
//         * any other parallel invocations of the search function are
//         * ignored.
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param searchFunction       a function returning a non-null
//         *                             result on success, else null
//         * @param <U>                  the return type of the search function
//         * @return a non-null result from applying the given search
//         * function on each entry, or null if none
//         * @since 1.8
//         */
//        public <U> U searchEntries(long parallelismThreshold, Function<Map.Entry<K, V>, ? extends U> searchFunction) {
//            if (searchFunction == null)
//                throw new NullPointerException();
//            return new SearchEntriesTask<K, V, U>(null, batchFor(parallelismThreshold), 0, 0, table, searchFunction, new AtomicReference<U>()).invoke();
//        }
//
//        /**
//         * Returns the result of accumulating all entries using the
//         * given reducer to combine values, or null if none.
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param reducer              a commutative associative combining function
//         * @return the result of accumulating all entries
//         * @since 1.8
//         */
//        public Map.Entry<K, V> reduceEntries(long parallelismThreshold, BiFunction<Map.Entry<K, V>, Map.Entry<K, V>, ? extends Map.Entry<K, V>> reducer) {
//            if (reducer == null)
//                throw new NullPointerException();
//            return new ReduceEntriesTask<K, V>(null, batchFor(parallelismThreshold), 0, 0, table, null, reducer).invoke();
//        }
//
//        /**
//         * Returns the result of accumulating the given transformation
//         * of all entries using the given reducer to combine values,
//         * or null if none.
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param transformer          a function returning the transformation
//         *                             for an element, or null if there is no transformation (in
//         *                             which case it is not combined)
//         * @param reducer              a commutative associative combining function
//         * @param <U>                  the return type of the transformer
//         * @return the result of accumulating the given transformation
//         * of all entries
//         * @since 1.8
//         */
//        public <U> U reduceEntries(long parallelismThreshold, Function<Map.Entry<K, V>, ? extends U> transformer, BiFunction<? super U, ? super U, ? extends U> reducer) {
//            if (transformer == null || reducer == null)
//                throw new NullPointerException();
//            return new MapReduceEntriesTask<K, V, U>(null, batchFor(parallelismThreshold), 0, 0, table, null, transformer, reducer).invoke();
//        }
//
//        /**
//         * Returns the result of accumulating the given transformation
//         * of all entries using the given reducer to combine values,
//         * and the given basis as an identity value.
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param transformer          a function returning the transformation
//         *                             for an element
//         * @param basis                the identity (initial default value) for the reduction
//         * @param reducer              a commutative associative combining function
//         * @return the result of accumulating the given transformation
//         * of all entries
//         * @since 1.8
//         */
//        public double reduceEntriesToDouble(long parallelismThreshold, ToDoubleFunction<Map.Entry<K, V>> transformer, double basis, DoubleBinaryOperator reducer) {
//            if (transformer == null || reducer == null)
//                throw new NullPointerException();
//            return new MapReduceEntriesToDoubleTask<K, V>(null, batchFor(parallelismThreshold), 0, 0, table, null, transformer, basis, reducer).invoke();
//        }
//
//        /**
//         * Returns the result of accumulating the given transformation
//         * of all entries using the given reducer to combine values,
//         * and the given basis as an identity value.
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param transformer          a function returning the transformation
//         *                             for an element
//         * @param basis                the identity (initial default value) for the reduction
//         * @param reducer              a commutative associative combining function
//         * @return the result of accumulating the given transformation
//         * of all entries
//         * @since 1.8
//         */
//        public long reduceEntriesToLong(long parallelismThreshold, ToLongFunction<Map.Entry<K, V>> transformer, long basis, LongBinaryOperator reducer) {
//            if (transformer == null || reducer == null)
//                throw new NullPointerException();
//            return new MapReduceEntriesToLongTask<K, V>(null, batchFor(parallelismThreshold), 0, 0, table, null, transformer, basis, reducer).invoke();
//        }
//
//        /**
//         * Returns the result of accumulating the given transformation
//         * of all entries using the given reducer to combine values,
//         * and the given basis as an identity value.
//         *
//         * @param parallelismThreshold the (estimated) number of elements
//         *                             needed for this operation to be executed in parallel
//         * @param transformer          a function returning the transformation
//         *                             for an element
//         * @param basis                the identity (initial default value) for the reduction
//         * @param reducer              a commutative associative combining function
//         * @return the result of accumulating the given transformation
//         * of all entries
//         * @since 1.8
//         */
//        public int reduceEntriesToInt(long parallelismThreshold, ToIntFunction<Map.Entry<K, V>> transformer, int basis, IntBinaryOperator reducer) {
//            if (transformer == null || reducer == null)
//                throw new NullPointerException();
//            return new MapReduceEntriesToIntTask<K, V>(null, batchFor(parallelismThreshold), 0, 0, table, null, transformer, basis, reducer).invoke();
//        }
//
//
//    /* ----------------Views -------------- */
//
//        /**
//         * Base class for views.
//         */
//        abstract static class CollectionView<K, V, E> implements Collection<E>, java.io.Serializable {
//            private static final long serialVersionUID = 7249069246763182397L;
//            final ConcurrentHashMap<K, V> map;
//
//            CollectionView(ConcurrentHashMap<K, V> map) {
//                this.map = map;
//            }
//
//            /**
//             * Returns the map backing this view.
//             *
//             * @return the map backing this view
//             */
//            public ConcurrentHashMap<K, V> getMap() {
//                return map;
//            }
//
//            /**
//             * Removes all of the elements from this view, by removing all
//             * the mappings from the map backing this view.
//             */
//            public final void clear() {
//                map.clear();
//            }
//
//            public final int size() {
//                return map.size();
//            }
//
//            public final boolean isEmpty() {
//                return map.isEmpty();
//            }
//
//            // implementations below rely on concrete classes supplying these
//            // abstract methods
//
//            /**
//             * Returns an iterator over the elements in this collection.
//             * <p>
//             * <p>The returned iterator is
//             * <a href="package-summary.html#Weakly"><i>weakly consistent</i></a>.
//             *
//             * @return an iterator over the elements in this collection
//             */
//            public abstract Iterator<E> iterator();
//
//            public abstract boolean contains(Object o);
//
//            public abstract boolean remove(Object o);
//
//            private static final String oomeMsg = "Required array size too large";
//
//            public final Object[] toArray() {
//                long sz = map.mappingCount();
//                if (sz > MAX_ARRAY_SIZE)
//                    throw new OutOfMemoryError(oomeMsg);
//                int n = (int) sz;
//                Object[] r = new Object[n];
//                int i = 0;
//                for (E e : this) {
//                    if (i == n) {
//                        if (n >= MAX_ARRAY_SIZE)
//                            throw new OutOfMemoryError(oomeMsg);
//                        if (n >= MAX_ARRAY_SIZE - (MAX_ARRAY_SIZE >>> 1) - 1)
//                            n = MAX_ARRAY_SIZE;
//                        else
//                            n += (n >>> 1) + 1;
//                        r = Arrays.copyOf(r, n);
//                    }
//                    r[i++] = e;
//                }
//                return (i == n) ? r : Arrays.copyOf(r, i);
//            }
//
//            @SuppressWarnings("unchecked")
//            public final <T> T[] toArray(T[] a) {
//                long sz = map.mappingCount();
//                if (sz > MAX_ARRAY_SIZE)
//                    throw new OutOfMemoryError(oomeMsg);
//                int m = (int) sz;
//                T[] r = (a.length >= m) ? a : (T[]) java.lang.reflect.Array.newInstance(a.getClass().getComponentType(), m);
//                int n = r.length;
//                int i = 0;
//                for (E e : this) {
//                    if (i == n) {
//                        if (n >= MAX_ARRAY_SIZE)
//                            throw new OutOfMemoryError(oomeMsg);
//                        if (n >= MAX_ARRAY_SIZE - (MAX_ARRAY_SIZE >>> 1) - 1)
//                            n = MAX_ARRAY_SIZE;
//                        else
//                            n += (n >>> 1) + 1;
//                        r = Arrays.copyOf(r, n);
//                    }
//                    r[i++] = (T) e;
//                }
//                if (a == r && i < n) {
//                    r[i] = null; // null-terminate
//                    return r;
//                }
//                return (i == n) ? r : Arrays.copyOf(r, i);
//            }
//
//            /**
//             * Returns a string representation of this collection.
//             * The string representation consists of the string representations
//             * of the collection's elements in the order they are returned by
//             * its iterator, enclosed in square brackets ({@code "[]"}).
//             * Adjacent elements are separated by the characters {@code ", "}
//             * (comma and space).  Elements are converted to strings as by
//             * {@link String#valueOf(Object)}.
//             *
//             * @return a string representation of this collection
//             */
//            public final String toString() {
//                StringBuilder sb = new StringBuilder();
//                sb.append('[');
//                Iterator<E> it = iterator();
//                if (it.hasNext()) {
//                    for (; ; ) {
//                        Object e = it.next();
//                        sb.append(e == this ? "(this Collection)" : e);
//                        if (!it.hasNext())
//                            break;
//                        sb.append(',').append(' ');
//                    }
//                }
//                return sb.append(']').toString();
//            }
//
//            public final boolean containsAll(Collection<?> c) {
//                if (c != this) {
//                    for (Object e : c) {
//                        if (e == null || !contains(e))
//                            return false;
//                    }
//                }
//                return true;
//            }
//
//            public final boolean removeAll(Collection<?> c) {
//                if (c == null)
//                    throw new NullPointerException();
//                boolean modified = false;
//                for (Iterator<E> it = iterator(); it.hasNext(); ) {
//                    if (c.contains(it.next())) {
//                        it.remove();
//                        modified = true;
//                    }
//                }
//                return modified;
//            }
//
//            public final boolean retainAll(Collection<?> c) {
//                if (c == null)
//                    throw new NullPointerException();
//                boolean modified = false;
//                for (Iterator<E> it = iterator(); it.hasNext(); ) {
//                    if (!c.contains(it.next())) {
//                        it.remove();
//                        modified = true;
//                    }
//                }
//                return modified;
//            }
//
//        }
//
//        /**
//         * A view of a ConcurrentHashMap as a {@link Set} of keys, in
//         * which additions may optionally be enabled by mapping to a
//         * common value.  This class cannot be directly instantiated.
//         * See {@link #keySet() keySet()},
//         * {@link #keySet(Object) keySet(V)},
//         * {@link #newKeySet() newKeySet()},
//         * {@link #newKeySet(int) newKeySet(int)}.
//         *
//         * @since 1.8
//         */
//        public static class KeySetView<K, V> extends CollectionView<K, V, K> implements Set<K>, java.io.Serializable {
//            private static final long serialVersionUID = 7249069246763182397L;
//            private final V value;
//
//            KeySetView(ConcurrentHashMap<K, V> map, V value) {  // non-public
//                super(map);
//                this.value = value;
//            }
//
//            /**
//             * Returns the default mapped value for additions,
//             * or {@code null} if additions are not supported.
//             *
//             * @return the default mapped value for additions, or {@code null}
//             * if not supported
//             */
//            public V getMappedValue() {
//                return value;
//            }
//
//            /**
//             * {@inheritDoc}
//             *
//             * @throws NullPointerException if the specified key is null
//             */
//            public boolean contains(Object o) {
//                return map.containsKey(o);
//            }
//
//            /**
//             * Removes the key from this map view, by removing the key (and its
//             * corresponding value) from the backing map.  This method does
//             * nothing if the key is not in the map.
//             *
//             * @param o the key to be removed from the backing map
//             * @return {@code true} if the backing map contained the specified key
//             * @throws NullPointerException if the specified key is null
//             */
//            public boolean remove(Object o) {
//                return map.remove(o) != null;
//            }
//
//            /**
//             * @return an iterator over the keys of the backing map
//             */
//            public Iterator<K> iterator() {
//                Node<K, V>[] t;
//                ConcurrentHashMap<K, V> m = map;
//                int f = (t = m.table) == null ? 0 : t.length;
//                return new KeyIterator<K, V>(t, f, 0, f, m);
//            }
//
//            /**
//             * Adds the specified key to this set view by mapping the key to
//             * the default mapped value in the backing map, if defined.
//             *
//             * @param e key to be added
//             * @return {@code true} if this set changed as a result of the call
//             * @throws NullPointerException          if the specified key is null
//             * @throws UnsupportedOperationException if no default mapped value
//             *                                       for additions was provided
//             */
//            public boolean add(K e) {
//                V v;
//                if ((v = value) == null)
//                    throw new UnsupportedOperationException();
//                return map.putVal(e, v, true) == null;
//            }
//
//            /**
//             * Adds all of the elements in the specified collection to this set,
//             * as if by calling {@link #add} on each one.
//             *
//             * @param c the elements to be inserted into this set
//             * @return {@code true} if this set changed as a result of the call
//             * @throws NullPointerException          if the collection or any of its
//             *                                       elements are {@code null}
//             * @throws UnsupportedOperationException if no default mapped value
//             *                                       for additions was provided
//             */
//            public boolean addAll(Collection<? extends K> c) {
//                boolean added = false;
//                V v;
//                if ((v = value) == null)
//                    throw new UnsupportedOperationException();
//                for (K e : c) {
//                    if (map.putVal(e, v, true) == null)
//                        added = true;
//                }
//                return added;
//            }
//
//            public int hashCode() {
//                int h = 0;
//                for (K e : this)
//                    h += e.hashCode();
//                return h;
//            }
//
//            public boolean equals(Object o) {
//                Set<?> c;
//                return ((o instanceof Set) && ((c = (Set<?>) o) == this || (containsAll(c) && c.containsAll(this))));
//            }
//
//            public Spliterator<K> spliterator() {
//                Node<K, V>[] t;
//                ConcurrentHashMap<K, V> m = map;
//                long n = m.sumCount();
//                int f = (t = m.table) == null ? 0 : t.length;
//                return new KeySpliterator<K, V>(t, f, 0, f, n < 0L ? 0L : n);
//            }
//
//            public void forEach(Consumer<? super K> action) {
//                if (action == null)
//                    throw new NullPointerException();
//                Node<K, V>[] t;
//                if ((t = map.table) != null) {
//                    Traverser<K, V> it = new Traverser<K, V>(t, t.length, 0, t.length);
//                    for (Node<K, V> p; (p = it.advance()) != null; )
//                        action.accept(p.key);
//                }
//            }
//        }
//
//        /**
//         * A view of a ConcurrentHashMap as a {@link Collection} of
//         * values, in which additions are disabled. This class cannot be
//         * directly instantiated. See {@link #values()}.
//         */
//        static final class ValuesView<K, V> extends CollectionView<K, V, V> implements Collection<V>, java.io.Serializable {
//            private static final long serialVersionUID = 2249069246763182397L;
//
//            ValuesView(ConcurrentHashMap<K, V> map) {
//                super(map);
//            }
//
//            public final boolean contains(Object o) {
//                return map.containsValue(o);
//            }
//
//            public final boolean remove(Object o) {
//                if (o != null) {
//                    for (Iterator<V> it = iterator(); it.hasNext(); ) {
//                        if (o.equals(it.next())) {
//                            it.remove();
//                            return true;
//                        }
//                    }
//                }
//                return false;
//            }
//
//            public final Iterator<V> iterator() {
//                ConcurrentHashMap<K, V> m = map;
//                Node<K, V>[] t;
//                int f = (t = m.table) == null ? 0 : t.length;
//                return new ValueIterator<K, V>(t, f, 0, f, m);
//            }
//
//            public final boolean add(V e) {
//                throw new UnsupportedOperationException();
//            }
//
//            public final boolean addAll(Collection<? extends V> c) {
//                throw new UnsupportedOperationException();
//            }
//
//            public Spliterator<V> spliterator() {
//                Node<K, V>[] t;
//                ConcurrentHashMap<K, V> m = map;
//                long n = m.sumCount();
//                int f = (t = m.table) == null ? 0 : t.length;
//                return new ValueSpliterator<K, V>(t, f, 0, f, n < 0L ? 0L : n);
//            }
//
//            public void forEach(Consumer<? super V> action) {
//                if (action == null)
//                    throw new NullPointerException();
//                Node<K, V>[] t;
//                if ((t = map.table) != null) {
//                    Traverser<K, V> it = new Traverser<K, V>(t, t.length, 0, t.length);
//                    for (Node<K, V> p; (p = it.advance()) != null; )
//                        action.accept(p.val);
//                }
//            }
//        }
//
//        /**
//         * A view of a ConcurrentHashMap as a {@link Set} of (key, value)
//         * entries.  This class cannot be directly instantiated. See
//         * {@link #entrySet()}.
//         */
//        static final class EntrySetView<K, V> extends CollectionView<K, V, Map.Entry<K, V>> implements Set<Map.Entry<K, V>>, java.io.Serializable {
//            private static final long serialVersionUID = 2249069246763182397L;
//
//            EntrySetView(ConcurrentHashMap<K, V> map) {
//                super(map);
//            }
//
//            public boolean contains(Object o) {
//                Object k, v, r;
//                Map.Entry<?, ?> e;
//                return ((o instanceof Map.Entry) && (k = (e = (Map.Entry<?, ?>) o).getKey()) != null && (r = map.get(k)) != null && (v = e.getValue()) != null && (v == r || v.equals(r)));
//            }
//
//            public boolean remove(Object o) {
//                Object k, v;
//                Map.Entry<?, ?> e;
//                return ((o instanceof Map.Entry) && (k = (e = (Map.Entry<?, ?>) o).getKey()) != null && (v = e.getValue()) != null && map.remove(k, v));
//            }
//
//            /**
//             * @return an iterator over the entries of the backing map
//             */
//            public Iterator<Map.Entry<K, V>> iterator() {
//                ConcurrentHashMap<K, V> m = map;
//                Node<K, V>[] t;
//                int f = (t = m.table) == null ? 0 : t.length;
//                return new EntryIterator<K, V>(t, f, 0, f, m);
//            }
//
//            public boolean add(Entry<K, V> e) {
//                return map.putVal(e.getKey(), e.getValue(), false) == null;
//            }
//
//            public boolean addAll(Collection<? extends Entry<K, V>> c) {
//                boolean added = false;
//                for (Entry<K, V> e : c) {
//                    if (add(e))
//                        added = true;
//                }
//                return added;
//            }
//
//            public final int hashCode() {
//                int h = 0;
//                Node<K, V>[] t;
//                if ((t = map.table) != null) {
//                    Traverser<K, V> it = new Traverser<K, V>(t, t.length, 0, t.length);
//                    for (Node<K, V> p; (p = it.advance()) != null; ) {
//                        h += p.hashCode();
//                    }
//                }
//                return h;
//            }
//
//            public final boolean equals(Object o) {
//                Set<?> c;
//                return ((o instanceof Set) && ((c = (Set<?>) o) == this || (containsAll(c) && c.containsAll(this))));
//            }
//
//            public Spliterator<Map.Entry<K, V>> spliterator() {
//                Node<K, V>[] t;
//                ConcurrentHashMap<K, V> m = map;
//                long n = m.sumCount();
//                int f = (t = m.table) == null ? 0 : t.length;
//                return new EntrySpliterator<K, V>(t, f, 0, f, n < 0L ? 0L : n, m);
//            }
//
//            public void forEach(Consumer<? super Map.Entry<K, V>> action) {
//                if (action == null)
//                    throw new NullPointerException();
//                Node<K, V>[] t;
//                if ((t = map.table) != null) {
//                    Traverser<K, V> it = new Traverser<K, V>(t, t.length, 0, t.length);
//                    for (Node<K, V> p; (p = it.advance()) != null; )
//                        action.accept(new MapEntry<K, V>(p.key, p.val, map));
//                }
//            }
//
//        }
//
//        // -------------------------------------------------------
//
//        /**
//         * Base class for bulk tasks. Repeats some fields and code from
//         * class Traverser, because we need to subclass CountedCompleter.
//         */
//        @SuppressWarnings("serial")
//        abstract static class BulkTask<K, V, R> extends CountedCompleter<R> {
//            Node<K, V>[] tab;        // same as Traverser
//            Node<K, V> next;
//            TableStack<K, V> stack, spare;
//            int index;
//            int baseIndex;
//            int baseLimit;
//            final int baseSize;
//            int batch;              // split control
//
//            BulkTask(BulkTask<K, V, ?> par, int b, int i, int f, Node<K, V>[] t) {
//                super(par);
//                this.batch = b;
//                this.index = this.baseIndex = i;
//                if ((this.tab = t) == null)
//                    this.baseSize = this.baseLimit = 0;
//                else if (par == null)
//                    this.baseSize = this.baseLimit = t.length;
//                else {
//                    this.baseLimit = f;
//                    this.baseSize = par.baseSize;
//                }
//            }
//
//            /**
//             * Same as Traverser version
//             */
//            final Node<K, V> advance() {
//                Node<K, V> e;
//                if ((e = next) != null)
//                    e = e.next;
//                for (; ; ) {
//                    Node<K, V>[] t;
//                    int i, n;
//                    if (e != null)
//                        return next = e;
//                    if (baseIndex >= baseLimit || (t = tab) == null || (n = t.length) <= (i = index) || i < 0)
//                        return next = null;
//                    if ((e = tabAt(t, i)) != null && e.hash < 0) {
//                        if (e instanceof ForwardingNode) {
//                            tab = ((ForwardingNode<K, V>) e).nextTable;
//                            e = null;
//                            pushState(t, i, n);
//                            continue;
//                        } else if (e instanceof TreeBin)
//                            e = ((TreeBin<K, V>) e).first;
//                        else
//                            e = null;
//                    }
//                    if (stack != null)
//                        recoverState(n);
//                    else if ((index = i + baseSize) >= n)
//                        index = ++baseIndex;
//                }
//            }
//
//            private void pushState(Node<K, V>[] t, int i, int n) {
//                TableStack<K, V> s = spare;
//                if (s != null)
//                    spare = s.next;
//                else
//                    s = new TableStack<K, V>();
//                s.tab = t;
//                s.length = n;
//                s.index = i;
//                s.next = stack;
//                stack = s;
//            }
//
//            private void recoverState(int n) {
//                TableStack<K, V> s;
//                int len;
//                while ((s = stack) != null && (index += (len = s.length)) >= n) {
//                    n = len;
//                    index = s.index;
//                    tab = s.tab;
//                    s.tab = null;
//                    TableStack<K, V> next = s.next;
//                    s.next = spare; // save for reuse
//                    stack = next;
//                    spare = s;
//                }
//                if (s == null && (index += baseSize) >= n)
//                    index = ++baseIndex;
//            }
//        }
//
//        /*
//     * Task classes. Coded in a regular but ugly format/style to
//     * simplify checks that each variant differs in the right way from
//     * others. The null screenings exist because compilers cannot tell
//     * that we've already null-checked task arguments, so we force
//     * simplest hoisted bypass to help avoid convoluted traps.
//     */
//        @SuppressWarnings("serial")
//        static final class ForEachKeyTask<K, V> extends BulkTask<K, V, Void> {
//            final Consumer<? super K> action;
//
//            ForEachKeyTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, Consumer<? super K> action) {
//                super(p, b, i, f, t);
//                this.action = action;
//            }
//
//            public final void compute() {
//                final Consumer<? super K> action;
//                if ((action = this.action) != null) {
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        addToPendingCount(1);
//                        new ForEachKeyTask<K, V>(this, batch >>>= 1, baseLimit = h, f, tab, action).fork();
//                    }
//                    for (Node<K, V> p; (p = advance()) != null; )
//                        action.accept(p.key);
//                    propagateCompletion();
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class ForEachValueTask<K, V> extends BulkTask<K, V, Void> {
//            final Consumer<? super V> action;
//
//            ForEachValueTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, Consumer<? super V> action) {
//                super(p, b, i, f, t);
//                this.action = action;
//            }
//
//            public final void compute() {
//                final Consumer<? super V> action;
//                if ((action = this.action) != null) {
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        addToPendingCount(1);
//                        new ForEachValueTask<K, V>(this, batch >>>= 1, baseLimit = h, f, tab, action).fork();
//                    }
//                    for (Node<K, V> p; (p = advance()) != null; )
//                        action.accept(p.val);
//                    propagateCompletion();
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class ForEachEntryTask<K, V> extends BulkTask<K, V, Void> {
//            final Consumer<? super Entry<K, V>> action;
//
//            ForEachEntryTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, Consumer<? super Entry<K, V>> action) {
//                super(p, b, i, f, t);
//                this.action = action;
//            }
//
//            public final void compute() {
//                final Consumer<? super Entry<K, V>> action;
//                if ((action = this.action) != null) {
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        addToPendingCount(1);
//                        new ForEachEntryTask<K, V>(this, batch >>>= 1, baseLimit = h, f, tab, action).fork();
//                    }
//                    for (Node<K, V> p; (p = advance()) != null; )
//                        action.accept(p);
//                    propagateCompletion();
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class ForEachMappingTask<K, V> extends BulkTask<K, V, Void> {
//            final BiConsumer<? super K, ? super V> action;
//
//            ForEachMappingTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, BiConsumer<? super K, ? super V> action) {
//                super(p, b, i, f, t);
//                this.action = action;
//            }
//
//            public final void compute() {
//                final BiConsumer<? super K, ? super V> action;
//                if ((action = this.action) != null) {
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        addToPendingCount(1);
//                        new ForEachMappingTask<K, V>(this, batch >>>= 1, baseLimit = h, f, tab, action).fork();
//                    }
//                    for (Node<K, V> p; (p = advance()) != null; )
//                        action.accept(p.key, p.val);
//                    propagateCompletion();
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class ForEachTransformedKeyTask<K, V, U> extends BulkTask<K, V, Void> {
//            final Function<? super K, ? extends U> transformer;
//            final Consumer<? super U> action;
//
//            ForEachTransformedKeyTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, Function<? super K, ? extends U> transformer, Consumer<? super U> action) {
//                super(p, b, i, f, t);
//                this.transformer = transformer;
//                this.action = action;
//            }
//
//            public final void compute() {
//                final Function<? super K, ? extends U> transformer;
//                final Consumer<? super U> action;
//                if ((transformer = this.transformer) != null && (action = this.action) != null) {
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        addToPendingCount(1);
//                        new ForEachTransformedKeyTask<K, V, U>(this, batch >>>= 1, baseLimit = h, f, tab, transformer, action).fork();
//                    }
//                    for (Node<K, V> p; (p = advance()) != null; ) {
//                        U u;
//                        if ((u = transformer.apply(p.key)) != null)
//                            action.accept(u);
//                    }
//                    propagateCompletion();
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class ForEachTransformedValueTask<K, V, U> extends BulkTask<K, V, Void> {
//            final Function<? super V, ? extends U> transformer;
//            final Consumer<? super U> action;
//
//            ForEachTransformedValueTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, Function<? super V, ? extends U> transformer, Consumer<? super U> action) {
//                super(p, b, i, f, t);
//                this.transformer = transformer;
//                this.action = action;
//            }
//
//            public final void compute() {
//                final Function<? super V, ? extends U> transformer;
//                final Consumer<? super U> action;
//                if ((transformer = this.transformer) != null && (action = this.action) != null) {
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        addToPendingCount(1);
//                        new ForEachTransformedValueTask<K, V, U>(this, batch >>>= 1, baseLimit = h, f, tab, transformer, action).fork();
//                    }
//                    for (Node<K, V> p; (p = advance()) != null; ) {
//                        U u;
//                        if ((u = transformer.apply(p.val)) != null)
//                            action.accept(u);
//                    }
//                    propagateCompletion();
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class ForEachTransformedEntryTask<K, V, U> extends BulkTask<K, V, Void> {
//            final Function<Map.Entry<K, V>, ? extends U> transformer;
//            final Consumer<? super U> action;
//
//            ForEachTransformedEntryTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, Function<Map.Entry<K, V>, ? extends U> transformer, Consumer<? super U> action) {
//                super(p, b, i, f, t);
//                this.transformer = transformer;
//                this.action = action;
//            }
//
//            public final void compute() {
//                final Function<Map.Entry<K, V>, ? extends U> transformer;
//                final Consumer<? super U> action;
//                if ((transformer = this.transformer) != null && (action = this.action) != null) {
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        addToPendingCount(1);
//                        new ForEachTransformedEntryTask<K, V, U>(this, batch >>>= 1, baseLimit = h, f, tab, transformer, action).fork();
//                    }
//                    for (Node<K, V> p; (p = advance()) != null; ) {
//                        U u;
//                        if ((u = transformer.apply(p)) != null)
//                            action.accept(u);
//                    }
//                    propagateCompletion();
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class ForEachTransformedMappingTask<K, V, U> extends BulkTask<K, V, Void> {
//            final BiFunction<? super K, ? super V, ? extends U> transformer;
//            final Consumer<? super U> action;
//
//            ForEachTransformedMappingTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, BiFunction<? super K, ? super V, ? extends U> transformer, Consumer<? super U> action) {
//                super(p, b, i, f, t);
//                this.transformer = transformer;
//                this.action = action;
//            }
//
//            public final void compute() {
//                final BiFunction<? super K, ? super V, ? extends U> transformer;
//                final Consumer<? super U> action;
//                if ((transformer = this.transformer) != null && (action = this.action) != null) {
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        addToPendingCount(1);
//                        new ForEachTransformedMappingTask<K, V, U>(this, batch >>>= 1, baseLimit = h, f, tab, transformer, action).fork();
//                    }
//                    for (Node<K, V> p; (p = advance()) != null; ) {
//                        U u;
//                        if ((u = transformer.apply(p.key, p.val)) != null)
//                            action.accept(u);
//                    }
//                    propagateCompletion();
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class SearchKeysTask<K, V, U> extends BulkTask<K, V, U> {
//            final Function<? super K, ? extends U> searchFunction;
//            final AtomicReference<U> result;
//
//            SearchKeysTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, Function<? super K, ? extends U> searchFunction, AtomicReference<U> result) {
//                super(p, b, i, f, t);
//                this.searchFunction = searchFunction;
//                this.result = result;
//            }
//
//            public final U getRawResult() {
//                return result.get();
//            }
//
//            public final void compute() {
//                final Function<? super K, ? extends U> searchFunction;
//                final AtomicReference<U> result;
//                if ((searchFunction = this.searchFunction) != null && (result = this.result) != null) {
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        if (result.get() != null)
//                            return;
//                        addToPendingCount(1);
//                        new SearchKeysTask<K, V, U>(this, batch >>>= 1, baseLimit = h, f, tab, searchFunction, result).fork();
//                    }
//                    while (result.get() == null) {
//                        U u;
//                        Node<K, V> p;
//                        if ((p = advance()) == null) {
//                            propagateCompletion();
//                            break;
//                        }
//                        if ((u = searchFunction.apply(p.key)) != null) {
//                            if (result.compareAndSet(null, u))
//                                quietlyCompleteRoot();
//                            break;
//                        }
//                    }
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class SearchValuesTask<K, V, U> extends BulkTask<K, V, U> {
//            final Function<? super V, ? extends U> searchFunction;
//            final AtomicReference<U> result;
//
//            SearchValuesTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, Function<? super V, ? extends U> searchFunction, AtomicReference<U> result) {
//                super(p, b, i, f, t);
//                this.searchFunction = searchFunction;
//                this.result = result;
//            }
//
//            public final U getRawResult() {
//                return result.get();
//            }
//
//            public final void compute() {
//                final Function<? super V, ? extends U> searchFunction;
//                final AtomicReference<U> result;
//                if ((searchFunction = this.searchFunction) != null && (result = this.result) != null) {
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        if (result.get() != null)
//                            return;
//                        addToPendingCount(1);
//                        new SearchValuesTask<K, V, U>(this, batch >>>= 1, baseLimit = h, f, tab, searchFunction, result).fork();
//                    }
//                    while (result.get() == null) {
//                        U u;
//                        Node<K, V> p;
//                        if ((p = advance()) == null) {
//                            propagateCompletion();
//                            break;
//                        }
//                        if ((u = searchFunction.apply(p.val)) != null) {
//                            if (result.compareAndSet(null, u))
//                                quietlyCompleteRoot();
//                            break;
//                        }
//                    }
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class SearchEntriesTask<K, V, U> extends BulkTask<K, V, U> {
//            final Function<Entry<K, V>, ? extends U> searchFunction;
//            final AtomicReference<U> result;
//
//            SearchEntriesTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, Function<Entry<K, V>, ? extends U> searchFunction, AtomicReference<U> result) {
//                super(p, b, i, f, t);
//                this.searchFunction = searchFunction;
//                this.result = result;
//            }
//
//            public final U getRawResult() {
//                return result.get();
//            }
//
//            public final void compute() {
//                final Function<Entry<K, V>, ? extends U> searchFunction;
//                final AtomicReference<U> result;
//                if ((searchFunction = this.searchFunction) != null && (result = this.result) != null) {
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        if (result.get() != null)
//                            return;
//                        addToPendingCount(1);
//                        new SearchEntriesTask<K, V, U>(this, batch >>>= 1, baseLimit = h, f, tab, searchFunction, result).fork();
//                    }
//                    while (result.get() == null) {
//                        U u;
//                        Node<K, V> p;
//                        if ((p = advance()) == null) {
//                            propagateCompletion();
//                            break;
//                        }
//                        if ((u = searchFunction.apply(p)) != null) {
//                            if (result.compareAndSet(null, u))
//                                quietlyCompleteRoot();
//                            return;
//                        }
//                    }
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class SearchMappingsTask<K, V, U> extends BulkTask<K, V, U> {
//            final BiFunction<? super K, ? super V, ? extends U> searchFunction;
//            final AtomicReference<U> result;
//
//            SearchMappingsTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, BiFunction<? super K, ? super V, ? extends U> searchFunction, AtomicReference<U> result) {
//                super(p, b, i, f, t);
//                this.searchFunction = searchFunction;
//                this.result = result;
//            }
//
//            public final U getRawResult() {
//                return result.get();
//            }
//
//            public final void compute() {
//                final BiFunction<? super K, ? super V, ? extends U> searchFunction;
//                final AtomicReference<U> result;
//                if ((searchFunction = this.searchFunction) != null && (result = this.result) != null) {
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        if (result.get() != null)
//                            return;
//                        addToPendingCount(1);
//                        new SearchMappingsTask<K, V, U>(this, batch >>>= 1, baseLimit = h, f, tab, searchFunction, result).fork();
//                    }
//                    while (result.get() == null) {
//                        U u;
//                        Node<K, V> p;
//                        if ((p = advance()) == null) {
//                            propagateCompletion();
//                            break;
//                        }
//                        if ((u = searchFunction.apply(p.key, p.val)) != null) {
//                            if (result.compareAndSet(null, u))
//                                quietlyCompleteRoot();
//                            break;
//                        }
//                    }
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class ReduceKeysTask<K, V> extends BulkTask<K, V, K> {
//            final BiFunction<? super K, ? super K, ? extends K> reducer;
//            K result;
//            ReduceKeysTask<K, V> rights, nextRight;
//
//            ReduceKeysTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, ReduceKeysTask<K, V> nextRight, BiFunction<? super K, ? super K, ? extends K> reducer) {
//                super(p, b, i, f, t);
//                this.nextRight = nextRight;
//                this.reducer = reducer;
//            }
//
//            public final K getRawResult() {
//                return result;
//            }
//
//            public final void compute() {
//                final BiFunction<? super K, ? super K, ? extends K> reducer;
//                if ((reducer = this.reducer) != null) {
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        addToPendingCount(1);
//                        (rights = new ReduceKeysTask<K, V>(this, batch >>>= 1, baseLimit = h, f, tab, rights, reducer)).fork();
//                    }
//                    K r = null;
//                    for (Node<K, V> p; (p = advance()) != null; ) {
//                        K u = p.key;
//                        r = (r == null) ? u : u == null ? r : reducer.apply(r, u);
//                    }
//                    result = r;
//                    CountedCompleter<?> c;
//                    for (c = firstComplete(); c != null; c = c.nextComplete()) {
//                        @SuppressWarnings("unchecked") ReduceKeysTask<K, V> t = (ReduceKeysTask<K, V>) c, s = t.rights;
//                        while (s != null) {
//                            K tr, sr;
//                            if ((sr = s.result) != null)
//                                t.result = (((tr = t.result) == null) ? sr : reducer.apply(tr, sr));
//                            s = t.rights = s.nextRight;
//                        }
//                    }
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class ReduceValuesTask<K, V> extends BulkTask<K, V, V> {
//            final BiFunction<? super V, ? super V, ? extends V> reducer;
//            V result;
//            ReduceValuesTask<K, V> rights, nextRight;
//
//            ReduceValuesTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, ReduceValuesTask<K, V> nextRight, BiFunction<? super V, ? super V, ? extends V> reducer) {
//                super(p, b, i, f, t);
//                this.nextRight = nextRight;
//                this.reducer = reducer;
//            }
//
//            public final V getRawResult() {
//                return result;
//            }
//
//            public final void compute() {
//                final BiFunction<? super V, ? super V, ? extends V> reducer;
//                if ((reducer = this.reducer) != null) {
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        addToPendingCount(1);
//                        (rights = new ReduceValuesTask<K, V>(this, batch >>>= 1, baseLimit = h, f, tab, rights, reducer)).fork();
//                    }
//                    V r = null;
//                    for (Node<K, V> p; (p = advance()) != null; ) {
//                        V v = p.val;
//                        r = (r == null) ? v : reducer.apply(r, v);
//                    }
//                    result = r;
//                    CountedCompleter<?> c;
//                    for (c = firstComplete(); c != null; c = c.nextComplete()) {
//                        @SuppressWarnings("unchecked") ReduceValuesTask<K, V> t = (ReduceValuesTask<K, V>) c, s = t.rights;
//                        while (s != null) {
//                            V tr, sr;
//                            if ((sr = s.result) != null)
//                                t.result = (((tr = t.result) == null) ? sr : reducer.apply(tr, sr));
//                            s = t.rights = s.nextRight;
//                        }
//                    }
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class ReduceEntriesTask<K, V> extends BulkTask<K, V, Map.Entry<K, V>> {
//            final BiFunction<Map.Entry<K, V>, Map.Entry<K, V>, ? extends Map.Entry<K, V>> reducer;
//            Map.Entry<K, V> result;
//            ReduceEntriesTask<K, V> rights, nextRight;
//
//            ReduceEntriesTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, ReduceEntriesTask<K, V> nextRight, BiFunction<Entry<K, V>, Map.Entry<K, V>, ? extends Map.Entry<K, V>> reducer) {
//                super(p, b, i, f, t);
//                this.nextRight = nextRight;
//                this.reducer = reducer;
//            }
//
//            public final Map.Entry<K, V> getRawResult() {
//                return result;
//            }
//
//            public final void compute() {
//                final BiFunction<Map.Entry<K, V>, Map.Entry<K, V>, ? extends Map.Entry<K, V>> reducer;
//                if ((reducer = this.reducer) != null) {
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        addToPendingCount(1);
//                        (rights = new ReduceEntriesTask<K, V>(this, batch >>>= 1, baseLimit = h, f, tab, rights, reducer)).fork();
//                    }
//                    Map.Entry<K, V> r = null;
//                    for (Node<K, V> p; (p = advance()) != null; )
//                        r = (r == null) ? p : reducer.apply(r, p);
//                    result = r;
//                    CountedCompleter<?> c;
//                    for (c = firstComplete(); c != null; c = c.nextComplete()) {
//                        @SuppressWarnings("unchecked") ReduceEntriesTask<K, V> t = (ReduceEntriesTask<K, V>) c, s = t.rights;
//                        while (s != null) {
//                            Map.Entry<K, V> tr, sr;
//                            if ((sr = s.result) != null)
//                                t.result = (((tr = t.result) == null) ? sr : reducer.apply(tr, sr));
//                            s = t.rights = s.nextRight;
//                        }
//                    }
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class MapReduceKeysTask<K, V, U> extends BulkTask<K, V, U> {
//            final Function<? super K, ? extends U> transformer;
//            final BiFunction<? super U, ? super U, ? extends U> reducer;
//            U result;
//            MapReduceKeysTask<K, V, U> rights, nextRight;
//
//            MapReduceKeysTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, MapReduceKeysTask<K, V, U> nextRight, Function<? super K, ? extends U> transformer, BiFunction<? super U, ? super U, ? extends U> reducer) {
//                super(p, b, i, f, t);
//                this.nextRight = nextRight;
//                this.transformer = transformer;
//                this.reducer = reducer;
//            }
//
//            public final U getRawResult() {
//                return result;
//            }
//
//            public final void compute() {
//                final Function<? super K, ? extends U> transformer;
//                final BiFunction<? super U, ? super U, ? extends U> reducer;
//                if ((transformer = this.transformer) != null && (reducer = this.reducer) != null) {
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        addToPendingCount(1);
//                        (rights = new MapReduceKeysTask<K, V, U>(this, batch >>>= 1, baseLimit = h, f, tab, rights, transformer, reducer)).fork();
//                    }
//                    U r = null;
//                    for (Node<K, V> p; (p = advance()) != null; ) {
//                        U u;
//                        if ((u = transformer.apply(p.key)) != null)
//                            r = (r == null) ? u : reducer.apply(r, u);
//                    }
//                    result = r;
//                    CountedCompleter<?> c;
//                    for (c = firstComplete(); c != null; c = c.nextComplete()) {
//                        @SuppressWarnings("unchecked") MapReduceKeysTask<K, V, U> t = (MapReduceKeysTask<K, V, U>) c, s = t.rights;
//                        while (s != null) {
//                            U tr, sr;
//                            if ((sr = s.result) != null)
//                                t.result = (((tr = t.result) == null) ? sr : reducer.apply(tr, sr));
//                            s = t.rights = s.nextRight;
//                        }
//                    }
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class MapReduceValuesTask<K, V, U> extends BulkTask<K, V, U> {
//            final Function<? super V, ? extends U> transformer;
//            final BiFunction<? super U, ? super U, ? extends U> reducer;
//            U result;
//            MapReduceValuesTask<K, V, U> rights, nextRight;
//
//            MapReduceValuesTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, MapReduceValuesTask<K, V, U> nextRight, Function<? super V, ? extends U> transformer, BiFunction<? super U, ? super U, ? extends U> reducer) {
//                super(p, b, i, f, t);
//                this.nextRight = nextRight;
//                this.transformer = transformer;
//                this.reducer = reducer;
//            }
//
//            public final U getRawResult() {
//                return result;
//            }
//
//            public final void compute() {
//                final Function<? super V, ? extends U> transformer;
//                final BiFunction<? super U, ? super U, ? extends U> reducer;
//                if ((transformer = this.transformer) != null && (reducer = this.reducer) != null) {
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        addToPendingCount(1);
//                        (rights = new MapReduceValuesTask<K, V, U>(this, batch >>>= 1, baseLimit = h, f, tab, rights, transformer, reducer)).fork();
//                    }
//                    U r = null;
//                    for (Node<K, V> p; (p = advance()) != null; ) {
//                        U u;
//                        if ((u = transformer.apply(p.val)) != null)
//                            r = (r == null) ? u : reducer.apply(r, u);
//                    }
//                    result = r;
//                    CountedCompleter<?> c;
//                    for (c = firstComplete(); c != null; c = c.nextComplete()) {
//                        @SuppressWarnings("unchecked") MapReduceValuesTask<K, V, U> t = (MapReduceValuesTask<K, V, U>) c, s = t.rights;
//                        while (s != null) {
//                            U tr, sr;
//                            if ((sr = s.result) != null)
//                                t.result = (((tr = t.result) == null) ? sr : reducer.apply(tr, sr));
//                            s = t.rights = s.nextRight;
//                        }
//                    }
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class MapReduceEntriesTask<K, V, U> extends BulkTask<K, V, U> {
//            final Function<Map.Entry<K, V>, ? extends U> transformer;
//            final BiFunction<? super U, ? super U, ? extends U> reducer;
//            U result;
//            MapReduceEntriesTask<K, V, U> rights, nextRight;
//
//            MapReduceEntriesTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, MapReduceEntriesTask<K, V, U> nextRight, Function<Map.Entry<K, V>, ? extends U> transformer, BiFunction<? super U, ? super U, ? extends U> reducer) {
//                super(p, b, i, f, t);
//                this.nextRight = nextRight;
//                this.transformer = transformer;
//                this.reducer = reducer;
//            }
//
//            public final U getRawResult() {
//                return result;
//            }
//
//            public final void compute() {
//                final Function<Map.Entry<K, V>, ? extends U> transformer;
//                final BiFunction<? super U, ? super U, ? extends U> reducer;
//                if ((transformer = this.transformer) != null && (reducer = this.reducer) != null) {
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        addToPendingCount(1);
//                        (rights = new MapReduceEntriesTask<K, V, U>(this, batch >>>= 1, baseLimit = h, f, tab, rights, transformer, reducer)).fork();
//                    }
//                    U r = null;
//                    for (Node<K, V> p; (p = advance()) != null; ) {
//                        U u;
//                        if ((u = transformer.apply(p)) != null)
//                            r = (r == null) ? u : reducer.apply(r, u);
//                    }
//                    result = r;
//                    CountedCompleter<?> c;
//                    for (c = firstComplete(); c != null; c = c.nextComplete()) {
//                        @SuppressWarnings("unchecked") MapReduceEntriesTask<K, V, U> t = (MapReduceEntriesTask<K, V, U>) c, s = t.rights;
//                        while (s != null) {
//                            U tr, sr;
//                            if ((sr = s.result) != null)
//                                t.result = (((tr = t.result) == null) ? sr : reducer.apply(tr, sr));
//                            s = t.rights = s.nextRight;
//                        }
//                    }
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class MapReduceMappingsTask<K, V, U> extends BulkTask<K, V, U> {
//            final BiFunction<? super K, ? super V, ? extends U> transformer;
//            final BiFunction<? super U, ? super U, ? extends U> reducer;
//            U result;
//            MapReduceMappingsTask<K, V, U> rights, nextRight;
//
//            MapReduceMappingsTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, MapReduceMappingsTask<K, V, U> nextRight, BiFunction<? super K, ? super V, ? extends U> transformer, BiFunction<? super U, ? super U, ? extends U> reducer) {
//                super(p, b, i, f, t);
//                this.nextRight = nextRight;
//                this.transformer = transformer;
//                this.reducer = reducer;
//            }
//
//            public final U getRawResult() {
//                return result;
//            }
//
//            public final void compute() {
//                final BiFunction<? super K, ? super V, ? extends U> transformer;
//                final BiFunction<? super U, ? super U, ? extends U> reducer;
//                if ((transformer = this.transformer) != null && (reducer = this.reducer) != null) {
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        addToPendingCount(1);
//                        (rights = new MapReduceMappingsTask<K, V, U>(this, batch >>>= 1, baseLimit = h, f, tab, rights, transformer, reducer)).fork();
//                    }
//                    U r = null;
//                    for (Node<K, V> p; (p = advance()) != null; ) {
//                        U u;
//                        if ((u = transformer.apply(p.key, p.val)) != null)
//                            r = (r == null) ? u : reducer.apply(r, u);
//                    }
//                    result = r;
//                    CountedCompleter<?> c;
//                    for (c = firstComplete(); c != null; c = c.nextComplete()) {
//                        @SuppressWarnings("unchecked") MapReduceMappingsTask<K, V, U> t = (MapReduceMappingsTask<K, V, U>) c, s = t.rights;
//                        while (s != null) {
//                            U tr, sr;
//                            if ((sr = s.result) != null)
//                                t.result = (((tr = t.result) == null) ? sr : reducer.apply(tr, sr));
//                            s = t.rights = s.nextRight;
//                        }
//                    }
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class MapReduceKeysToDoubleTask<K, V> extends BulkTask<K, V, Double> {
//            final ToDoubleFunction<? super K> transformer;
//            final DoubleBinaryOperator reducer;
//            final double basis;
//            double result;
//            MapReduceKeysToDoubleTask<K, V> rights, nextRight;
//
//            MapReduceKeysToDoubleTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, MapReduceKeysToDoubleTask<K, V> nextRight, ToDoubleFunction<? super K> transformer, double basis, DoubleBinaryOperator reducer) {
//                super(p, b, i, f, t);
//                this.nextRight = nextRight;
//                this.transformer = transformer;
//                this.basis = basis;
//                this.reducer = reducer;
//            }
//
//            public final Double getRawResult() {
//                return result;
//            }
//
//            public final void compute() {
//                final ToDoubleFunction<? super K> transformer;
//                final DoubleBinaryOperator reducer;
//                if ((transformer = this.transformer) != null && (reducer = this.reducer) != null) {
//                    double r = this.basis;
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        addToPendingCount(1);
//                        (rights = new MapReduceKeysToDoubleTask<K, V>(this, batch >>>= 1, baseLimit = h, f, tab, rights, transformer, r, reducer)).fork();
//                    }
//                    for (Node<K, V> p; (p = advance()) != null; )
//                        r = reducer.applyAsDouble(r, transformer.applyAsDouble(p.key));
//                    result = r;
//                    CountedCompleter<?> c;
//                    for (c = firstComplete(); c != null; c = c.nextComplete()) {
//                        @SuppressWarnings("unchecked") MapReduceKeysToDoubleTask<K, V> t = (MapReduceKeysToDoubleTask<K, V>) c, s = t.rights;
//                        while (s != null) {
//                            t.result = reducer.applyAsDouble(t.result, s.result);
//                            s = t.rights = s.nextRight;
//                        }
//                    }
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class MapReduceValuesToDoubleTask<K, V> extends BulkTask<K, V, Double> {
//            final ToDoubleFunction<? super V> transformer;
//            final DoubleBinaryOperator reducer;
//            final double basis;
//            double result;
//            MapReduceValuesToDoubleTask<K, V> rights, nextRight;
//
//            MapReduceValuesToDoubleTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, MapReduceValuesToDoubleTask<K, V> nextRight, ToDoubleFunction<? super V> transformer, double basis, DoubleBinaryOperator reducer) {
//                super(p, b, i, f, t);
//                this.nextRight = nextRight;
//                this.transformer = transformer;
//                this.basis = basis;
//                this.reducer = reducer;
//            }
//
//            public final Double getRawResult() {
//                return result;
//            }
//
//            public final void compute() {
//                final ToDoubleFunction<? super V> transformer;
//                final DoubleBinaryOperator reducer;
//                if ((transformer = this.transformer) != null && (reducer = this.reducer) != null) {
//                    double r = this.basis;
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        addToPendingCount(1);
//                        (rights = new MapReduceValuesToDoubleTask<K, V>(this, batch >>>= 1, baseLimit = h, f, tab, rights, transformer, r, reducer)).fork();
//                    }
//                    for (Node<K, V> p; (p = advance()) != null; )
//                        r = reducer.applyAsDouble(r, transformer.applyAsDouble(p.val));
//                    result = r;
//                    CountedCompleter<?> c;
//                    for (c = firstComplete(); c != null; c = c.nextComplete()) {
//                        @SuppressWarnings("unchecked") MapReduceValuesToDoubleTask<K, V> t = (MapReduceValuesToDoubleTask<K, V>) c, s = t.rights;
//                        while (s != null) {
//                            t.result = reducer.applyAsDouble(t.result, s.result);
//                            s = t.rights = s.nextRight;
//                        }
//                    }
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class MapReduceEntriesToDoubleTask<K, V> extends BulkTask<K, V, Double> {
//            final ToDoubleFunction<Map.Entry<K, V>> transformer;
//            final DoubleBinaryOperator reducer;
//            final double basis;
//            double result;
//            MapReduceEntriesToDoubleTask<K, V> rights, nextRight;
//
//            MapReduceEntriesToDoubleTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, MapReduceEntriesToDoubleTask<K, V> nextRight, ToDoubleFunction<Map.Entry<K, V>> transformer, double basis, DoubleBinaryOperator reducer) {
//                super(p, b, i, f, t);
//                this.nextRight = nextRight;
//                this.transformer = transformer;
//                this.basis = basis;
//                this.reducer = reducer;
//            }
//
//            public final Double getRawResult() {
//                return result;
//            }
//
//            public final void compute() {
//                final ToDoubleFunction<Map.Entry<K, V>> transformer;
//                final DoubleBinaryOperator reducer;
//                if ((transformer = this.transformer) != null && (reducer = this.reducer) != null) {
//                    double r = this.basis;
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        addToPendingCount(1);
//                        (rights = new MapReduceEntriesToDoubleTask<K, V>(this, batch >>>= 1, baseLimit = h, f, tab, rights, transformer, r, reducer)).fork();
//                    }
//                    for (Node<K, V> p; (p = advance()) != null; )
//                        r = reducer.applyAsDouble(r, transformer.applyAsDouble(p));
//                    result = r;
//                    CountedCompleter<?> c;
//                    for (c = firstComplete(); c != null; c = c.nextComplete()) {
//                        @SuppressWarnings("unchecked") MapReduceEntriesToDoubleTask<K, V> t = (MapReduceEntriesToDoubleTask<K, V>) c, s = t.rights;
//                        while (s != null) {
//                            t.result = reducer.applyAsDouble(t.result, s.result);
//                            s = t.rights = s.nextRight;
//                        }
//                    }
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class MapReduceMappingsToDoubleTask<K, V> extends BulkTask<K, V, Double> {
//            final ToDoubleBiFunction<? super K, ? super V> transformer;
//            final DoubleBinaryOperator reducer;
//            final double basis;
//            double result;
//            MapReduceMappingsToDoubleTask<K, V> rights, nextRight;
//
//            MapReduceMappingsToDoubleTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, MapReduceMappingsToDoubleTask<K, V> nextRight, ToDoubleBiFunction<? super K, ? super V> transformer, double basis, DoubleBinaryOperator reducer) {
//                super(p, b, i, f, t);
//                this.nextRight = nextRight;
//                this.transformer = transformer;
//                this.basis = basis;
//                this.reducer = reducer;
//            }
//
//            public final Double getRawResult() {
//                return result;
//            }
//
//            public final void compute() {
//                final ToDoubleBiFunction<? super K, ? super V> transformer;
//                final DoubleBinaryOperator reducer;
//                if ((transformer = this.transformer) != null && (reducer = this.reducer) != null) {
//                    double r = this.basis;
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        addToPendingCount(1);
//                        (rights = new MapReduceMappingsToDoubleTask<K, V>(this, batch >>>= 1, baseLimit = h, f, tab, rights, transformer, r, reducer)).fork();
//                    }
//                    for (Node<K, V> p; (p = advance()) != null; )
//                        r = reducer.applyAsDouble(r, transformer.applyAsDouble(p.key, p.val));
//                    result = r;
//                    CountedCompleter<?> c;
//                    for (c = firstComplete(); c != null; c = c.nextComplete()) {
//                        @SuppressWarnings("unchecked") MapReduceMappingsToDoubleTask<K, V> t = (MapReduceMappingsToDoubleTask<K, V>) c, s = t.rights;
//                        while (s != null) {
//                            t.result = reducer.applyAsDouble(t.result, s.result);
//                            s = t.rights = s.nextRight;
//                        }
//                    }
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class MapReduceKeysToLongTask<K, V> extends BulkTask<K, V, Long> {
//            final ToLongFunction<? super K> transformer;
//            final LongBinaryOperator reducer;
//            final long basis;
//            long result;
//            MapReduceKeysToLongTask<K, V> rights, nextRight;
//
//            MapReduceKeysToLongTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, MapReduceKeysToLongTask<K, V> nextRight, ToLongFunction<? super K> transformer, long basis, LongBinaryOperator reducer) {
//                super(p, b, i, f, t);
//                this.nextRight = nextRight;
//                this.transformer = transformer;
//                this.basis = basis;
//                this.reducer = reducer;
//            }
//
//            public final Long getRawResult() {
//                return result;
//            }
//
//            public final void compute() {
//                final ToLongFunction<? super K> transformer;
//                final LongBinaryOperator reducer;
//                if ((transformer = this.transformer) != null && (reducer = this.reducer) != null) {
//                    long r = this.basis;
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        addToPendingCount(1);
//                        (rights = new MapReduceKeysToLongTask<K, V>(this, batch >>>= 1, baseLimit = h, f, tab, rights, transformer, r, reducer)).fork();
//                    }
//                    for (Node<K, V> p; (p = advance()) != null; )
//                        r = reducer.applyAsLong(r, transformer.applyAsLong(p.key));
//                    result = r;
//                    CountedCompleter<?> c;
//                    for (c = firstComplete(); c != null; c = c.nextComplete()) {
//                        @SuppressWarnings("unchecked") MapReduceKeysToLongTask<K, V> t = (MapReduceKeysToLongTask<K, V>) c, s = t.rights;
//                        while (s != null) {
//                            t.result = reducer.applyAsLong(t.result, s.result);
//                            s = t.rights = s.nextRight;
//                        }
//                    }
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class MapReduceValuesToLongTask<K, V> extends BulkTask<K, V, Long> {
//            final ToLongFunction<? super V> transformer;
//            final LongBinaryOperator reducer;
//            final long basis;
//            long result;
//            MapReduceValuesToLongTask<K, V> rights, nextRight;
//
//            MapReduceValuesToLongTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, MapReduceValuesToLongTask<K, V> nextRight, ToLongFunction<? super V> transformer, long basis, LongBinaryOperator reducer) {
//                super(p, b, i, f, t);
//                this.nextRight = nextRight;
//                this.transformer = transformer;
//                this.basis = basis;
//                this.reducer = reducer;
//            }
//
//            public final Long getRawResult() {
//                return result;
//            }
//
//            public final void compute() {
//                final ToLongFunction<? super V> transformer;
//                final LongBinaryOperator reducer;
//                if ((transformer = this.transformer) != null && (reducer = this.reducer) != null) {
//                    long r = this.basis;
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        addToPendingCount(1);
//                        (rights = new MapReduceValuesToLongTask<K, V>(this, batch >>>= 1, baseLimit = h, f, tab, rights, transformer, r, reducer)).fork();
//                    }
//                    for (Node<K, V> p; (p = advance()) != null; )
//                        r = reducer.applyAsLong(r, transformer.applyAsLong(p.val));
//                    result = r;
//                    CountedCompleter<?> c;
//                    for (c = firstComplete(); c != null; c = c.nextComplete()) {
//                        @SuppressWarnings("unchecked") MapReduceValuesToLongTask<K, V> t = (MapReduceValuesToLongTask<K, V>) c, s = t.rights;
//                        while (s != null) {
//                            t.result = reducer.applyAsLong(t.result, s.result);
//                            s = t.rights = s.nextRight;
//                        }
//                    }
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class MapReduceEntriesToLongTask<K, V> extends BulkTask<K, V, Long> {
//            final ToLongFunction<Map.Entry<K, V>> transformer;
//            final LongBinaryOperator reducer;
//            final long basis;
//            long result;
//            MapReduceEntriesToLongTask<K, V> rights, nextRight;
//
//            MapReduceEntriesToLongTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, MapReduceEntriesToLongTask<K, V> nextRight, ToLongFunction<Map.Entry<K, V>> transformer, long basis, LongBinaryOperator reducer) {
//                super(p, b, i, f, t);
//                this.nextRight = nextRight;
//                this.transformer = transformer;
//                this.basis = basis;
//                this.reducer = reducer;
//            }
//
//            public final Long getRawResult() {
//                return result;
//            }
//
//            public final void compute() {
//                final ToLongFunction<Map.Entry<K, V>> transformer;
//                final LongBinaryOperator reducer;
//                if ((transformer = this.transformer) != null && (reducer = this.reducer) != null) {
//                    long r = this.basis;
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        addToPendingCount(1);
//                        (rights = new MapReduceEntriesToLongTask<K, V>(this, batch >>>= 1, baseLimit = h, f, tab, rights, transformer, r, reducer)).fork();
//                    }
//                    for (Node<K, V> p; (p = advance()) != null; )
//                        r = reducer.applyAsLong(r, transformer.applyAsLong(p));
//                    result = r;
//                    CountedCompleter<?> c;
//                    for (c = firstComplete(); c != null; c = c.nextComplete()) {
//                        @SuppressWarnings("unchecked") MapReduceEntriesToLongTask<K, V> t = (MapReduceEntriesToLongTask<K, V>) c, s = t.rights;
//                        while (s != null) {
//                            t.result = reducer.applyAsLong(t.result, s.result);
//                            s = t.rights = s.nextRight;
//                        }
//                    }
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class MapReduceMappingsToLongTask<K, V> extends BulkTask<K, V, Long> {
//            final ToLongBiFunction<? super K, ? super V> transformer;
//            final LongBinaryOperator reducer;
//            final long basis;
//            long result;
//            MapReduceMappingsToLongTask<K, V> rights, nextRight;
//
//            MapReduceMappingsToLongTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, MapReduceMappingsToLongTask<K, V> nextRight, ToLongBiFunction<? super K, ? super V> transformer, long basis, LongBinaryOperator reducer) {
//                super(p, b, i, f, t);
//                this.nextRight = nextRight;
//                this.transformer = transformer;
//                this.basis = basis;
//                this.reducer = reducer;
//            }
//
//            public final Long getRawResult() {
//                return result;
//            }
//
//            public final void compute() {
//                final ToLongBiFunction<? super K, ? super V> transformer;
//                final LongBinaryOperator reducer;
//                if ((transformer = this.transformer) != null && (reducer = this.reducer) != null) {
//                    long r = this.basis;
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        addToPendingCount(1);
//                        (rights = new MapReduceMappingsToLongTask<K, V>(this, batch >>>= 1, baseLimit = h, f, tab, rights, transformer, r, reducer)).fork();
//                    }
//                    for (Node<K, V> p; (p = advance()) != null; )
//                        r = reducer.applyAsLong(r, transformer.applyAsLong(p.key, p.val));
//                    result = r;
//                    CountedCompleter<?> c;
//                    for (c = firstComplete(); c != null; c = c.nextComplete()) {
//                        @SuppressWarnings("unchecked") MapReduceMappingsToLongTask<K, V> t = (MapReduceMappingsToLongTask<K, V>) c, s = t.rights;
//                        while (s != null) {
//                            t.result = reducer.applyAsLong(t.result, s.result);
//                            s = t.rights = s.nextRight;
//                        }
//                    }
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class MapReduceKeysToIntTask<K, V> extends BulkTask<K, V, Integer> {
//            final ToIntFunction<? super K> transformer;
//            final IntBinaryOperator reducer;
//            final int basis;
//            int result;
//            MapReduceKeysToIntTask<K, V> rights, nextRight;
//
//            MapReduceKeysToIntTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, MapReduceKeysToIntTask<K, V> nextRight, ToIntFunction<? super K> transformer, int basis, IntBinaryOperator reducer) {
//                super(p, b, i, f, t);
//                this.nextRight = nextRight;
//                this.transformer = transformer;
//                this.basis = basis;
//                this.reducer = reducer;
//            }
//
//            public final Integer getRawResult() {
//                return result;
//            }
//
//            public final void compute() {
//                final ToIntFunction<? super K> transformer;
//                final IntBinaryOperator reducer;
//                if ((transformer = this.transformer) != null && (reducer = this.reducer) != null) {
//                    int r = this.basis;
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        addToPendingCount(1);
//                        (rights = new MapReduceKeysToIntTask<K, V>(this, batch >>>= 1, baseLimit = h, f, tab, rights, transformer, r, reducer)).fork();
//                    }
//                    for (Node<K, V> p; (p = advance()) != null; )
//                        r = reducer.applyAsInt(r, transformer.applyAsInt(p.key));
//                    result = r;
//                    CountedCompleter<?> c;
//                    for (c = firstComplete(); c != null; c = c.nextComplete()) {
//                        @SuppressWarnings("unchecked") MapReduceKeysToIntTask<K, V> t = (MapReduceKeysToIntTask<K, V>) c, s = t.rights;
//                        while (s != null) {
//                            t.result = reducer.applyAsInt(t.result, s.result);
//                            s = t.rights = s.nextRight;
//                        }
//                    }
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class MapReduceValuesToIntTask<K, V> extends BulkTask<K, V, Integer> {
//            final ToIntFunction<? super V> transformer;
//            final IntBinaryOperator reducer;
//            final int basis;
//            int result;
//            MapReduceValuesToIntTask<K, V> rights, nextRight;
//
//            MapReduceValuesToIntTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, MapReduceValuesToIntTask<K, V> nextRight, ToIntFunction<? super V> transformer, int basis, IntBinaryOperator reducer) {
//                super(p, b, i, f, t);
//                this.nextRight = nextRight;
//                this.transformer = transformer;
//                this.basis = basis;
//                this.reducer = reducer;
//            }
//
//            public final Integer getRawResult() {
//                return result;
//            }
//
//            public final void compute() {
//                final ToIntFunction<? super V> transformer;
//                final IntBinaryOperator reducer;
//                if ((transformer = this.transformer) != null && (reducer = this.reducer) != null) {
//                    int r = this.basis;
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        addToPendingCount(1);
//                        (rights = new MapReduceValuesToIntTask<K, V>(this, batch >>>= 1, baseLimit = h, f, tab, rights, transformer, r, reducer)).fork();
//                    }
//                    for (Node<K, V> p; (p = advance()) != null; )
//                        r = reducer.applyAsInt(r, transformer.applyAsInt(p.val));
//                    result = r;
//                    CountedCompleter<?> c;
//                    for (c = firstComplete(); c != null; c = c.nextComplete()) {
//                        @SuppressWarnings("unchecked") MapReduceValuesToIntTask<K, V> t = (MapReduceValuesToIntTask<K, V>) c, s = t.rights;
//                        while (s != null) {
//                            t.result = reducer.applyAsInt(t.result, s.result);
//                            s = t.rights = s.nextRight;
//                        }
//                    }
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class MapReduceEntriesToIntTask<K, V> extends BulkTask<K, V, Integer> {
//            final ToIntFunction<Map.Entry<K, V>> transformer;
//            final IntBinaryOperator reducer;
//            final int basis;
//            int result;
//            MapReduceEntriesToIntTask<K, V> rights, nextRight;
//
//            MapReduceEntriesToIntTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, MapReduceEntriesToIntTask<K, V> nextRight, ToIntFunction<Map.Entry<K, V>> transformer, int basis, IntBinaryOperator reducer) {
//                super(p, b, i, f, t);
//                this.nextRight = nextRight;
//                this.transformer = transformer;
//                this.basis = basis;
//                this.reducer = reducer;
//            }
//
//            public final Integer getRawResult() {
//                return result;
//            }
//
//            public final void compute() {
//                final ToIntFunction<Map.Entry<K, V>> transformer;
//                final IntBinaryOperator reducer;
//                if ((transformer = this.transformer) != null && (reducer = this.reducer) != null) {
//                    int r = this.basis;
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        addToPendingCount(1);
//                        (rights = new MapReduceEntriesToIntTask<K, V>(this, batch >>>= 1, baseLimit = h, f, tab, rights, transformer, r, reducer)).fork();
//                    }
//                    for (Node<K, V> p; (p = advance()) != null; )
//                        r = reducer.applyAsInt(r, transformer.applyAsInt(p));
//                    result = r;
//                    CountedCompleter<?> c;
//                    for (c = firstComplete(); c != null; c = c.nextComplete()) {
//                        @SuppressWarnings("unchecked") MapReduceEntriesToIntTask<K, V> t = (MapReduceEntriesToIntTask<K, V>) c, s = t.rights;
//                        while (s != null) {
//                            t.result = reducer.applyAsInt(t.result, s.result);
//                            s = t.rights = s.nextRight;
//                        }
//                    }
//                }
//            }
//        }
//
//        @SuppressWarnings("serial")
//        static final class MapReduceMappingsToIntTask<K, V> extends BulkTask<K, V, Integer> {
//            final ToIntBiFunction<? super K, ? super V> transformer;
//            final IntBinaryOperator reducer;
//            final int basis;
//            int result;
//            MapReduceMappingsToIntTask<K, V> rights, nextRight;
//
//            MapReduceMappingsToIntTask(BulkTask<K, V, ?> p, int b, int i, int f, Node<K, V>[] t, MapReduceMappingsToIntTask<K, V> nextRight, ToIntBiFunction<? super K, ? super V> transformer, int basis, IntBinaryOperator reducer) {
//                super(p, b, i, f, t);
//                this.nextRight = nextRight;
//                this.transformer = transformer;
//                this.basis = basis;
//                this.reducer = reducer;
//            }
//
//            public final Integer getRawResult() {
//                return result;
//            }
//
//            public final void compute() {
//                final ToIntBiFunction<? super K, ? super V> transformer;
//                final IntBinaryOperator reducer;
//                if ((transformer = this.transformer) != null && (reducer = this.reducer) != null) {
//                    int r = this.basis;
//                    for (int i = baseIndex, f, h; batch > 0 && (h = ((f = baseLimit) + i) >>> 1) > i; ) {
//                        addToPendingCount(1);
//                        (rights = new MapReduceMappingsToIntTask<K, V>(this, batch >>>= 1, baseLimit = h, f, tab, rights, transformer, r, reducer)).fork();
//                    }
//                    for (Node<K, V> p; (p = advance()) != null; )
//                        r = reducer.applyAsInt(r, transformer.applyAsInt(p.key, p.val));
//                    result = r;
//                    CountedCompleter<?> c;
//                    for (c = firstComplete(); c != null; c = c.nextComplete()) {
//                        @SuppressWarnings("unchecked") MapReduceMappingsToIntTask<K, V> t = (MapReduceMappingsToIntTask<K, V>) c, s = t.rights;
//                        while (s != null) {
//                            t.result = reducer.applyAsInt(t.result, s.result);
//                            s = t.rights = s.nextRight;
//                        }
//                    }
//                }
//            }
//        }
//
//        // Unsafe mechanics
//        private static final sun.misc.Unsafe U;
//        private static final long SIZECTL;
//        private static final long TRANSFERINDEX;
//        private static final long BASECOUNT;
//        private static final long CELLSBUSY;
//        private static final long CELLVALUE;
//        private static final long ABASE;
//        private static final int ASHIFT;
//
//        static {
//            try {
//                U = sun.misc.Unsafe.getUnsafe();
//                Class<?> k = ConcurrentHashMap.class;
//                SIZECTL = U.objectFieldOffset(k.getDeclaredField("sizeCtl"));
//                TRANSFERINDEX = U.objectFieldOffset(k.getDeclaredField("transferIndex"));
//                BASECOUNT = U.objectFieldOffset(k.getDeclaredField("baseCount"));
//                CELLSBUSY = U.objectFieldOffset(k.getDeclaredField("cellsBusy"));
//                Class<?> ck = CounterCell.class;
//                CELLVALUE = U.objectFieldOffset(ck.getDeclaredField("value"));
//                Class<?> ak = Node[].class;
//                ABASE = U.arrayBaseOffset(ak);
//                int scale = U.arrayIndexScale(ak);
//                if ((scale & (scale - 1)) != 0)
//                    throw new Error("data type scale not a power of two");
//                ASHIFT = 31 - Integer.numberOfLeadingZeros(scale);
//            } catch (Exception e) {
//                throw new Error(e);
//            }
//        }
//    }
//
//
//}
